'So they wouldn't get out of the Chimera, would they?' If Lakon's terminator helm could look cynical and slightly depressed, it would. As it did the captain had to settle for a ceramite growl instead.

'No my lord,' Kodos said. The tent flaps stirred in the wind. Sunlight streamed in. Shadows passed as people hurried busily by. Engines rumbled outside as vehicles moved around. The air smelt of machine exhaust, mud and human sweat. Hard-packed earth was under their feet, with a few mangled blades of grass lingering here and there. The many feet of the assembled army hadn't been good to this field. To their left was a rickety field table. Several maps were sat on it, along with a dribbling votive candle. The candle had gone out a couple of hours previously. A fat blob of wax had dribbled over one of the maps.

'Great.' Lakon wasn't impressed. 'I had a feeling it would come down to us.'

'My lord?'

'You might call it natural selection,' Lakon said. 'We're left with the Guardsmen bright enough to frag the Commissar. The rest of them are probably dead by now. Problem is, it means this lot are bright enough to have a sense of self-preservation.'

Kodos sighed. 'It's probably true. How inconvenient.'

'Oh well. At least this lot also had the wit to phone home when they spotted something odd. It could be worse.'

'Could it?'

'Yes, Sergeant. We might not know there was anything loose in the forest.'

'So there are Nids, north of the valley,' Kodos said. 'How did they get there?'

'I think that's pretty obvious.'

'Is it, my lord?'

'Yes. Aerial patrols haven't seen anything. The nearest settlements didn't report anything odd before our arrival. Surveillance images taken before deployment show nothing north of the mountains.'

'That doesn't leave anything … obvious to me, Captain.'

Lakon sighed. 'There must be a tunnel. How else did they cross the valley?'

'Oh.' Kodos rolled his eyes. 'Skak me. You're right. That's where all the buggy bastards have been the last few hours, isn't it?'

Lakon's helm nodded. 'Digging. Yes. And all the while we were scratching our heads, wondering why the Gap had gone quiet. The skakking bugs were probably right under our feet at that very moment. The foul things were probably laughing at us the whole way!'

'I don't think they do that, my lord. Clack their mandibles, perhaps.'

'Yes, thank you, Kodos,' Lakon said acerbically. 'And the plan is obvious enough. Mine the dam. When the Guard arrives, blow it. Drown them all as they cross the valley.'

Kodos scowled. 'And they almost managed it, too.'

'Looks like we have your lads to thank for paying attention,' Lakon agreed. 'I'm glad someone was.'

Kodos nodded slowly. 'Of course we assumed that there were no bugs near the dam. So we didn't look. If we had, we might've seen them.'

'I think,' Lakon said, 'that maybe we're showing too much faith in our assumptions. I wonder what else we're missing?'

'My lord,' Kodos said carefully, 'I know it's not my place, but…' He trailed off.

'Skak your place,' Lakon said. 'Spit it.'

'The overall battle plan depends on the Guard, doesn't it?'

'We're not expecting anything from the infantry, if that's what you mean. I'll be happy if any of them show up, to be honest.'

'But the artillery are critical.'

'Yes. We need the Basilisks, to thin the bugs out. At the moment we're outnumbered eight thousand to one-'

'That's gone up.'

'New images,' Lakon replied. 'The weather's a bit better. The horde's swollen. Seems it's sucking in every bug for miles around. Anyway, if we can cut that down to a few hundred to one then we can manage.'

Kodos patted the butt of his pistol. 'I'll take a few hundred Nids any day.'

'I'm sure you will, Sergeant. My point is, no-one's planning anything on the assumption of any help from the Guard infantry.'

'And the PDF?'

Lakon shrugged. 'A non-issue. The surviving regiments are mostly trying to hold the Shervan Delta. That's over a thousand clicks away. They won't be here – they can't be here.'

'And the Octalian troops?'

'We're garrisoning the north with them.'

'Couldn't they be used more?'

'No.' Lakon shook his head. 'They're better fighters than the locals, and they're braver – but they're not Ravens. Frankly, I think we may have asked too much of them as it is. This isn't really their fight, and it never was. The Octalian formations are at breaking point. They've been going on as long as we have, don't forget. If we're to have any use out of them in the future, they need some respite.'

Kodos nodded with reluctance. 'I suppose that's true.'

'So, everything rests on the Guard artillery.'

'When do they start arriving?'

'The latest schedule says this afternoon,' Lakon said. 'Right here...' He pointed to one of the maps on the table, then stopped. 'Right where that big fat blob of wax is, in fact.'

'Great. So even the candle's got it in for us?'

Lakon tried to pick the thing up. It had stuck itself to the map. It lifted half off the table. With a rustle of paper, a cascade of documents slithered to the muddy floor.

Lakon let loose a string of profanities.

Kodos lifted up the tent flap. He blinked briefly in the brighter light, then signalled to a passing Chapter serf. 'You. Get this stuff of the floor for us.'

The man twitched, surprised, but threw off a passable salute. 'Yes sir.' He ducked into the tent and set about clearing up the mess.

'I was going to point out a location seven hundred metres north of here,' Lakon explained.

'Is that where the Guard are going?'

Lakon nodded. 'Yes. It's got a ridge and good sightlines. There aren't any trees to get in the way. It's behind our lines, so it shouldn't have any attacks – oh, skak.'

'There's our assumption,' Kodos said.

'So it is.' Lakon looked frustrated. 'What's the betting the hive mind's guessed our strategy?'

'I'd give you about evens on that,' Kodos said. He glanced at the map. 'And I notice those woods we were at earlier – the north end is just below that ridge. Don't quote me on this, but that's where our tunnel'll be.'

Lakon sighed. 'I have a horrible feeling you might be right.'

'So … when do the artillery show up?'

'The schedule's advanced. They're due at 1530 this afternoon.'

'Thank the Emperor for that.'

Lakon nodded. 'But it puts us on a schedule. We need the Nids rooted out by then. And it's 1240 now.'

'Skak. Well, with your permission, I'll take my squad out there right now. We'll get to scouting the area. Since we're here right now, we might as well.'

Lakon nodded. 'I can get some extra help for you. Not much, but we'll have to make do.'

* * *

A roughly-triangular shadow appeared on the ground. Engines growled. A grey landspeeder dropped in next to Alaster. Literally next to him – the wing was a foot behind him and he could reach out and touch the side of the cockpit. As precision flying went, it was impressive.

He managed not to start too visibly.

'What-?'

'Hello,' said the Space Marine sat inside the cockpit next to him. 'Remember us?'

Alaster stared at the grey helmet, glad that the other marine couldn't see his own perplexity.

Hang on. Grey armour – Space Wolves, then. Einar Thorbjornsson's, obviously. And a Mark Six helmet, Alaster noted. And a running wolf on the marine's breastplate-

'Haakon!'

'Well he remembers you,' Eirik said grumpily, from Haakon's other side.

'And you owe me a flagon of ale,' Haakon added cheerfully. To Alaster he said, 'Eirik didn't think you'd recognise us. I said never bet against your allies.'

The squad was briefly back at the camp. No sooner had they done disarming the bomb then Kodos had felt it was time for Lakon to be informed. They'd been waiting at the edge of the tents.

Nasty and Patreus were suddenly at Alaster's side.

'Hey, it's good to see you!' Nasty said.

'You too. I see you've still got the axe.'

Nasty brandished it with enthusiasm. 'I'm not losing this!'

'I hope you've been putting it to good use.'

'It's split plenty of bug-heads, if that counts?'

Haakon laughed. 'It'll do.'

Nearby, the flaps of a tent swirled. Kodos marched out. He strode over. His shadow preceded him on the churned soil. He took in the landspeeder without any apparent surprise. 'Good,' he said. 'We've got another little job to do.' He nodded at the landspeeder. 'And some reinforcements to help us out.'

'Hi,' Eirik said. 'Don't mind us. It's not like we were doing anything important.'

'Somewhere near where the artillery are going, there's a bug hole,' Kodos explained. 'We need to find it.' There was a meltabomb hung from his belt. He patted it. His gauntlet clinked against the dull metal. 'And do a bit of landscaping, if you take my meaning.'

'That's how they got into the wood, isn't it?' Alaster asked, comprehension dawning.

Kodos nodded. 'Snuck from the hole to the trees – yes. So no-one saw them.'

'Bad bugs,' Haakon put in. 'No biscuit.'

'Anyway,' Kodos said, 'we need to move. Now.'

A short flight ensued. They quickly found themselves approaching the ridge. 'Look!' Sandrer said. 'They're already there!'

'Skak,' Kodos muttered. 'They're early!'

And they were, too. Guardsmen were swarming over the grass, setting up. Alaster could see mortars and gun emplacements. Behind them big artillery pieces were being assembled. Gun barrels were being checked and readied. Ammunition was being unloaded from trucks. The ridge was a mass of activity. Further back tents were being erected.

'How did that happen?' Eirik asked.

'We'd better drop in,' Haakon said.

'I agree,' Kodos said.

The marines dropped in at the edge of the growing encampment. Their presence elicited less attention then it would anywhere else. A few of the Guard had a look, but they had plenty of other things to do.

A few quick questions from Kodos got the location of the commander here. The colonel, it turned out, was far too busy to speak to them but one of his sub-alterns apparently had time. The marines found themselves stood outside an olive-grey tent, feeling somewhat out of place amidst the sea of identically-uniformed Guardsmen. Haakon and Eirik took the landspeeder back up above the camp, patrolling around the ridge.

After a surprisingly-long wait, the designated officer put in an appearance. He came out of the tent, apparently still in the process of clipping his moustache. Alaster found himself watching the spectacle with a growing feeling of disbelief. What was happening? The man didn't even look at Kodos – he just carried on peering into his portable mirror, snipping away with a small pair of scissors. He didn't smell of blood or sweat. Instead he smelt of fine unguents and expensive aftershave. Alaster also noted a suspicious lack of anything even dimly resembling scar tissue. Inside his helmet, the Space Marine frowned. Since when did an Imperial officer look like a court fop who'd never been shot at?

'What?' the man asked, not even looking up from his snipping

'We have a message for whoever's in charge here,' Kodos said bluntly, 'assuming they have the time to take it, of course.' There was an edge in his voice.

The officer appeared not to notice. 'We are so busy, as you might see,' he said, snipping away.

'You're early,' Kodos noted. 'We weren't expecting you for a couple more hours.'

The man shrugged. 'We made better time then we expected.' Snip, snip went the blades of the scissors.

'It'd be useful if we got to hear these things.'

'We had a lot of preparation to do, on the way down. The vox wasn't the highest priority. Is that all you're here for?'

'No. Just some information to pass on.'

'Oh. What are you complaining about, then?'

'I'm sorry?'

'Well, if you haven't called in to tell us something we should know, how can you complain at us? Typical Marine behaviour. You expect everything but offer nothing in return. You're not above the rules, you know. However much you might think you are.'

Kodos was quiet for a moment. Then: 'Well, since we're here, would you like to hear what we have to say – or not?'

Snip, snip.

The man shrugged. 'To be honest, I doubt it's that important.' He waved his scissors. 'I was rather busy. It is so important to maintain an authoritative personal appearance, you know.' He looked pointedly at Kodos's breastplate. 'If you walk around with your uniform covered in dents, however can your men respect you?' He smirked. Alaster could barely believe this performance. The casual rudeness was breathtaking. What was more, it was delivered with a maddeningly-calm arrogance. Before anyone could say anything else, the man spoke again. 'Well, if you must hang around, spit it out. What is this dazzling revelation?'

'You'd be advised,' Kodos said, 'to mount patrols. There've been reports of Nid activity in this area.'

Snip. Finally the man paused his trimming. He held the mirror and the scissors away from his face. There was cynical scorn in his eyes. 'Rubbish. There are no Nids here.'

'I beg your pardon?' The edge in Kodos' voice was an angry one now.

'I said-'

'We saw them ourselves,' Kodos cut in. 'Not an hour ago.'

The officer shrugged. 'Why are you standing here then, sergeant?'

Kodos was silent for a moment. 'Because, if you hadn't noticed, we're trying to give you some warning.'

'If you'd done your job in the first place,' the man said with a complacent sneer, 'we wouldn't need "warning" as you put it.'

Alaster realised his hand was on his chainsword. The other Ravens were all reaching for their guns, he noticed. Kodos looked at them. 'Stand down!' he barked. He looked back at the subaltern. 'And what was that meant to mean, Second Lieutenant?'

The man twitched, as if a blow had finally landed. 'First Lieutenant,' he growled. 'And you were supposed to be holding the Gap. If the Bugs have got through, it means you haven't. Sergeant.'

Kodos was silent for a moment. Then he said, 'Well. See that your master knows, Guardsman.'

This time the man jerked. His brows clenched with anger. His fingers spasmed. The scissors fell unnoticed to the floor. 'How dare-'

'Oh, I'm sorry,' Kodos said with false reasonableness. 'The uniform confused me. I assumed you were an office of the Imperial Guard, hence my referring to you as such. But if you're some random off the street instead…?'

The man was staring with flat hate now. 'I think you should take your leave, Sergeant,' he said.

'If you insist,' Kodos said. 'But make sure your master gets his message.' Without a further word he fired his jump pack. The squad followed.

As the tent dwindled beneath them, Alaster let out the breath he'd been holding onto. He knew, of course, that these sorts of feuds sometimes happened. Defending the Imperium was a stressful business under any circumstances, let alone ones like these, and it was no surprise that tempers could rise. That little display, however, had been truly petty. How did someone that unreasonable make it through the day?

'If I see him in a bug's mouth,' Nasty said suddenly, 'I won't do a damned thing. Chomp, chomp, problem solved.'

'Brother Sandy,' Kodos said, 'you will do whatever you're skakking told. Even if that does include rescuing that fool.'

'It'd be worth it,' Eorvan put in, 'to see his face when he has to thank a Marine. I reckon it'd stick in his craw.'

There was a grumble of engines. The landspeeder drew alongside. 'Hello,' Haakon said. 'We saw all of that. Well done on not scragging that bastard, Kodos.'

'Yes,' Eirik added, 'I don't think my bolter would suffer an insult like that.'

'He obviously has a problem with Space Marines,' Kodos said carefully, 'and for all we actually know, there might be something behind it. Let's face it, some of our forces haven't behaved too well over the last few months.'

'We all know about the Blueys,' Haakon put in.

'I don't want to start a blood feud with our allies,' Kodos said. 'And I particularly don't if it's possible we're just reaping something we've sown.'

'Like what, exactly?' demanded Sandrer. 'Sergeant, he used your title like it was an insult.'

Kodos sighed. 'It's a problem with some Guard officers. Because he's a lieutenant and I'm a sergeant, he thinks he outranks me. It probably frustrates him that he can't give marines orders, the way he's used to. Probably feels it's an inversion of the natural order, or something. What he doesn't see, of course, is the centuries of experience or the things I've had to take down. And if he's lucky, he never will see any of the latter.'

''Specially not if they get behind him,' Eirik put in. 'Splat!' Haakon laughed.

'So what are we going to do?' Alaster asked.

'What we planned in the first place,' Kodos replied. 'Scout the area. Try and find the tunnel.'

'Do you think he'll tell the colonel?'

'I assume so. He's asserted his perceived authority now. Once he calms down he'll see sense.'

'And if he doesn't?'

'Then the bugs eat a few Guardsmen. And later on an investigation happens. And his malfeasance comes to light. And then he goes on gallows leave. No, he'll tell the colonel. I'm sure he understands enlightened self-interest, if maybe not much else. He'll make sure his arse is covered.'

Nasty snorted a laugh. 'He is an arse.'

'On a practical level,' Kodos said, 'we'll start our search over by the woods. I'm guessing that's most likely where the tunnel is. Shortest distance and all of that.'

They flew over to the woods. The ridge gave way with a steep slope, down to thickets of bushes and shrubs near its base. The trees started a short way back. They were some small ponds, presumably formed of rainfall runoff from the slope. In places it was muddy underfoot.

Unlike much of the rest of Riothria, here the vegetation seemed relatively healthy. Alaster noticed they were sheltered from the wind here behind the ridge, but it was also south-facing. Even this near the equator, that would make a difference. Possibly this explained the continued survival of the vegetation.

The small force split itself into three parts – the Space Wolves with the landspeeder and the two fireteams. They each took a different third of the interface between ridge and forest. That way it shouldn't take too long to scour. Due to the dense foliage, they'd have to do their scouting from the ground. It would be too easy to miss a small opening while passing above. Alaster, Patreus and Nasty had the furthest of the three segments.

They started without further delay.

A few minutes after, muddy ground squished under Alaster's boot.

'Hey, try and be quieter!' Nasty said. 'Every Nid in the woods must have heard that noise!'

They were at the bottom of the slope. The grassy bank rose up to their left. At Alaster's right were the first shrubs and, not far behind, the densely-packed trees trunks. Leafy canopies rose above. Somewhere in there, a bird was tweeting.

In their immediate vicinity, the ground was boggy. Right before Alaster was a big puddle, at least ten feet across. It was several inches deep in places. Rippling reflections of the Ravens and their surroundings swirled on its surface. Alaster's boot had partly sunk into the mud right at the edge.

Alaster looked at it. 'There's plenty more where that came from.' Carefully he withdrew his feet. The mud made a quiet sucking sound. Brown water swirled into the depression.

Patreus, oddly enough, was looking intently at one of the trees. 'They don't look tropical,' he noted. 'It's not a jungle, like that place back on Delta. You know, the training camp.'

'That's weird,' Nasty said. 'Aren't we near the equator?'

Alaster hesitated. 'I gather it's not the same here. There are cold currents in the seas near here, and strong winds, you know, higher up in the air. They take a lot of heat away from here, and the ocean currents cool things down. It doesn't get so warm at the equator on Minoris. I think they said just an even twenty-five degrees, not the thirty or forty you'd get on Delta. But on the other hand, because so much heat's going north and far south, it doesn't get too cold up there either.'

'We've been all over this planet,' Patreus noted, 'and I haven't seen anything like tundra, I suppose.'

'There were polar caps,' Nasty said stubbornly. 'All the pictures had them.'

'And you only look at the pictures, don't you?' Patreus said teasingly. 'I mean, that reading thing … that'd be a bit much, wouldn't it?'

Alaster felt the need to intervene. 'There are polar caps,' he explained, 'but they're small. In a way, I guess it's why the impact winter's been so bad. The stuff that lives here just isn't used to big temperature changes.'

Nasty snorted. 'So the planet's weak as well. Well that explains a bit.'

'It's not like home,' Patreus said.

'No. And why would it be? Look how different they are, just around Octalis.'

'I wonder if it's anything like Terra?' Nasty said suddenly. 'Or was, I mean.'

Patreus stared at him. 'Wow. That actually sounded like a thought just happened there. You're spending too much time around Brother Alaster, Nasty. You've been infected.'

Alaster ignored Patreus. 'To a point,' he supposed. 'I mean, people can live here – the air isn't poisoning them and the gravity doesn't skak up their bones, or anything like that. Or at least, not much.'

'Not much?' Nasty asked.

'The life expectancy is decades, not minutes,' Alaster clarified.

'It can't all be roses,' Nasty said.

'It can be but I'm sure there are still thorns,' Alaster agreed.

'What?' Nasty sounded confused. 'The planet has thorns?'

It took Alaster a moment to realise that Nasty hadn't understood his metaphor. 'No – not literally. What I meant is, there will be illnesses. Odd things you get here and nowhere else. Because there's something in the air or the soil that isn't quite right. They do screen planets for these things, but there's only so much you can control for.'

'Well I'm glad our home system isn't like that.'

Alaster laughed. 'Are you joking?'

Nasty paused and looked at him. 'So there is something wrong?'

'Lots of things wrong. You remember Gamma, right? Not remotely enough water, and not really enough air. Just look at the populations. More than three hundred times as many people live on Delta. That's not a healthy sign.'

'Eta always looks pretty in the pictures.'

'Are you kidding? It hits minus thirty in the winters. And that's near the equator. A third of its surface is ice. It's only habitable at all because there's crap in the air, keeping the heat in. The trees can't flush it through properly – there's not enough of them, with so much ice on the land. Loads of people there have lung problems. And with all that permafrost, the farming isn't so good.'

'I thought all the rich people live there,' Patreus said.

'Sure, the rich all go there for their chalets and winter holidays but they all have air units plugged in the ceilings, flushing out the excess cee-oh-two. Again, look at the populations. It's still better than Gamma, but "better" is still only a few hundred million. I mean, it looks pretty in the holos, with all the mountains and the snow, but there's serious downsides to all that too.'

'Well Delta's okay.'

'No it isn't.'

'Isn't it?'

Alaster shook his head. 'Okay, the air's clean, there's enough water and it's not too hot and not too cold. But there's other stuff as well. Do you remember those pills they give you at school, you know, the little grey ones?'

'Oh, I know those!' Patreus put in. 'We got them at the monastery. I bit one once. It was disgusting.'

'They're supplements of something called potassium,' Alaster explained. 'The whole Octalian System is deficient in it. Apparently if you don't get enough of it, it does something to your nerves. Makes you retarded or something.'

'You seem to know a lot about it.'

'I spent half an hour a day for an entire year filing reports on potassium shipments. The Administratum took it pretty seriously. The shipments cost the government sixteen billion a year. The Assembly had a special budget for it.'

Nasty was quiet for a time. Then he said: 'We never got those at any schools I went to.'

'You went to school?' Patreus sounded surprised.

'Yeah, briefly. Six of 'em.'

'Six?'

'Yeah, got thrown out of each of them.'

'You've really done the rounds, haven't you?'

'Yeah. And I never saw no pills.' Nasty was quiet for a moment. 'I wonder if that's why there were so many thick kids around.'

'Well, maybe that explains a bit about you,' Patreus said.

'Oi!' Nasty said. 'That was mean!' He grabbed up a small pebble and threw it at Patreus. Patreus batted it aside without a second glance.

Alaster looked at Nasty. 'There were oddities in the balances,' he said.

'What do you mean?'

'The budget was projected to cover costs for the whole population … but it never quite did. There were always shortfalls. They said it was down to exchange rates and tariffs and price fluctuations, but I did always wonder.'

'Wonder what?' Patreus asked.

'There were people at the office on the fiddle,' Alaster said, uncomfortable memories bubbling up. 'Petty things, like claiming their taxis on the expenses. You can sort of see why they did it. The Administratum has job security but it's not that well-paid.'

'What, service is it's own reward?' Nasty asked in a snarky tone.

'That's what they'd say,' Alaster agreed.

'That's what they tell us,' Patreus pointed out.

'Yeah, but we don't have rent or water and gas bills as well. Or healthcare. Our material needs are met. We don't ever need to worry about stuff like that. Whereas in the world of work … one badly-timed illness can ruin you, unless you're in with your boss and he holds your job for you. You can see why people might be tempted to cook the books. I don't like it, but you can see why it happens. Frankly, if they paid the lower staff a sensible wage, there'd be less temptation to fiddle.'

'Yeah but try getting that past the voters at an election,' Patreus observed. 'Payrises for bureaucrats.'

There was silence for a moment. A bird twittered somewhere in the bushes. 'So what about the pills?' Nasty said at last.

'I wondered if some of the budget was being stolen,' Alaster said in a rush.

'Oh, surprise, surprise.' Nasty was sarcastic. 'That'd be the newsflash of the week, that would.'

Patreus shifted awkwardly from one foot to the other. 'And of course the place the money would go from is lower down the scale. The bottom-levelled families. Who have fewer votes and worse jobs and fewer opportunities. The ones who can't kick up as much fuss. And probably the people who need it the most. Brothers, I think we've just spotted a hole in Delta's social system.'

'Uh,' Nasty said gently, 'it's not exactly news.'

Alaster nodded. 'Yeah. People've been writing books about this sort of thing for centuries.'

'Then … why hasn't anything been done?' Patreus sounded frustrated. 'It isn't right.'

'It's not that easy to clean up,' Alaster explained, feeling uncomfortable. 'There are a lot of planets in the Imperium. There's no one source for the goods. Many of them do have tariffs and prices do fluctuate. To clean the system up completely you'd need to account for all of that stuff. And have perfect foreknowledge of what the system'll do in the future. Only then could you definitely identify the fraud. And that's impossible. Of course you can get the more blatant offenders. And the less cautious. And you can make examples of them and try and discourage others. But you can never root it out absolutely. I guess it's the old problem of being finite human beings, really.'

'Speak for yourself,' Nasty grumbled.

Feeling a bit lame, Alaster decided to try and wrap it up. 'I guess we just have to try and manage, really, as best we can. Things are never going to be perfect.'

Nasty looked in his direction. Alaster suspected he might be glaring inside his helmet. 'Easy for you to say. You weren't on the receiving end.'

Alaster rapped his knuckles on the eagle on his breastplate. 'We all are, now.'

Patreus was staring off to the side. 'Hey,' he said, 'talking of things being imperfect – is it just me or does that bush look weird?'

He was pointing further down the hillside. There was a single bush, sprouting from the hillside. It was a fat, bulbous thing. Small, pointy leaves sprouted from its branches. They were a greyish-green in colour. The bush was fat but it was casting a very large shadow.

Hang on. The shadow was too large.

'There's a hole behind it,' Alaster realised.

It took but moments to ascertain the truth. There was indeed a big, gaping hole next to the bush. Most of it was covered by the dense foliage. That was why it hadn't been seen from the air. The rest of the discolouration would probably just be written off as dropped leaves from the plant or something.

The three Ravens found themselves grouped around the hole. It was quickly revealed that the hole sank back into the ridge.

'It's going the wrong way,' Nasty said.

'I suspect it turns,' Alaster said. 'Let's have a look. Patreus, wait here and watch the entrance. Nasty, you're with me.'

The hole was just big enough to fit a fully-armed Space Marine. Given that it had to accommodate two of them, this was probably just as well. Loose soil and a few dead leaves crunched under their boots as they entered. It quickly darkened inside. The entrance remained as a bright circle behind them. The tunnel was cool and damp. The air smelt of soil and mouldy roots.

Alaster had to be careful where he put his feet. The crown of his jump pack kept scraping the ceiling, resulting in small showers of loose earth.

'What's that?' Nasty pointed at something ahead of them.

Alaster looked at it. It looked a bit like a rib, a sort of bony arch. It was embedded in the floor, its two ribs curving together at the ceiling. The ribs had cilia, resembling roots, threading into the floor. It looked like it had grown in place.

'A ceiling prop,' Alaster said. 'I think.' Whether it was that or something else, it was obviously Tyranid in origin. It just didn't look like anything any sort of human being might make.

Nasty reached for his pistol.

'Stop,' Alaster said. 'We don't want to bring the ceiling down on us, do we?'

'Oh.' Nasty sounded slightly abashed. 'Hey, look at that!' He gestured to the floor.

Alaster looked. Sunk into the compacted soil below was a footprint. Or perhaps a pawprint – Alaster wasn't sure which was more appropriate. What wasn't in doubt was its origin.

'Genestealers,' he said. 'So they were here, then. Presumably this is how the Gargoyles came through too. They must've crawled or something.'

They moved slightly further down the tunnel, passing a couple more of the props. They came to a bend in the tunnel. It curved off to the side and downwards.

'There's your answer,' Alaster said. 'It does indeed turn. I suppose it must run all the way back under the river and out onto the other side of the mountains. I suppose they curved it so they could hide the opening in the side of the bank.'

'Why here?' Nasty asked. 'Why not closer to the lake?'

Alaster hesitated. 'Maybe they were trying to scout our lines as well. Kill two birds with one stone. Mine the dam and get a look at what we were doing.'

'Do you think we should go on?'

'Are you mad? I might be fearless but I'm not stupid. No, the sensible course is get the meltas off Kodos and bring down the corridor. We know where it goes. Nothing to be gained by blundering around in the dark.'

'Fair point.' Nasty paused. 'Is it just me or can I hear something?'

'I don't know – can you?' Alaster listened in all the same. Now that Nasty mentioned it, there was a faint noise. A sort of rhythmic throbbing, very quiet. He rested a hand on one of the earthen walls of the corridor. Yes, he could feel it, just a little. 'Yeah, there is something.'

'Wonder what it is?'

'I wonder if it's one of the machines up with the Guard? The sound might go a way, you know, through the ground.'

Nasty considered that for a moment. 'Okay, I suppose that's what it must be. Let's get back.'

A short while later, they emerged back into the welcome daylight. Leaves were rustling in the breeze and some more birds were chirping away somewhere in the undergrowth. The freshness of the air was a welcome change from the close, underground scent.

'What did you find?' Patreus asked.

'It's empty now, but it's definitely buggy,' Alaster replied. 'On that note, let's fetch Kodos.'

The sergeant and the rest of the force arrived shortly. Alaster briefly explained what they'd seen. Kodos merely nodded. He didn't consider the sounds significant either. 'Best to collapse it near the turn, then,' he said. 'If we weaken the props after that, they should come down easily enough.'

Weakening the props turned out to consist of spitting on them. The bony substance they were made of was acid-resistant but only to a point. A certain amount of hissing and fizzing later and a visible sag developed in each strut. It might not have eaten clean through them, but the acid did weaken them.

Finally the meltabomb was placed in the corridor, at the bend. Kodos thumbed its little timer and they quickly retreated, back out of the tunnel.

Moments later there was a rumble. A puff of dust erupted from the tunnel. Then, almost gently, the grass above sagged down. Displaced soil grumbled down. An overspill dribbled out of the tunnel mouth. And that was it. The Tyranid tunnel was plugged.

'That was a bit anticlimactic,' Sandrer commented.

'Well what were you expecting?' Kodos asked. 'The entire hill to go boom? No lads, this will do. It's sealed now.'

Nasty walked over to the mound of displaced earth. He squatted down, resting a hand on it. 'Hey, I can still feel that rumbling!' he said.

'You must be imagining it,' Alaster said. 'Get up.'

'Okay,' Kodos said. 'We need to head back.' He looked at the landspeeder, hovering nearby. 'Haakon, Eirik, thanks for your help. I owe you one, although it looks like we didn't need you this time.'

Haakon's beaky helmet aimed itself at the hill. It tilted to one side, as if considering something. 'Hang on,' he said.

'What is it, Brother?'

Haakon vaulted out of the landspeeder. He landed on the ground with a thud. He tugged off his helmet and squatted down. Long locks of hair fell past his face. He put an ear to the ground, looking increasingly disturbed. After a moment, he looked up. 'That's not Guard machinery, Brothers,' he said. 'Someone's drilling up.'

'What?' Kodos sounded surprised. 'Up? Where from?'

'If I had to guess,' Haakon said, 'somewhere under there!' He pointed at the ridge.

A horrible realisation hit Alaster. 'The tunnel. It was empty and unguarded.'

'Oh skak,' Kodos said. 'They've moved on!'

'We need to warn the Guard,' Eorvan said.

Haakon retrieved his helmet and climbed back into the landspeeder. His harness clicked back into place. The landspeeder rose.

The assault marines followed it. The ridge dropped below them. Afternoon sunlight was washing over it. The Guard were still busy setting up.

'The colonel's tent is over there,' Kodos said, pointing. 'I don't care if he thinks he's too busy – he's going to have to find time!'

They flew toward the camp.

Grass was undulating in the wind below them when everything went wrong. Fegust saw it first. 'Look!' he shouted, gesturing wildly.

Near one of the Guard tents, the grass was rippling. It was literally rippling, like a stone dropped into a pond. Some immense force was rhythmically smashing into it from below. Alaster watched in horror as a puzzled Guardsman stopped nearby. The man was carrying a shell. Zooming his eyelenses in, Alaster could see the confusion on the man's face as he looked at the grass. Alaster could almost imagine what was running through the man's head. Grass wasn't meant to ripple! And what was this thrumming he could feel through his feet?

A conical mound of distorted earth rose. Suddenly it split. A fountain of loose pebbles and torn roots spewed up. The tip of the Nid boring creature erupted into the sunlight.

The Guardsman stared in horror at the thing. It was a sort of bony cone, like the material of the props. It was lined with sharp, curving protrusions. Presumably they were the digging surfaces. From the shape of the thing, it looked like it dug through rotation, boring the soil away. With another powerful thrust, the alien cone burst further through the soil. Now there was more than two metres of it, sticking up into the air.

Alaster willed his jump pack to move faster, but to no response. The fans were spinning as hard as they could already.

The cone twitched. Then it split open, like an obscene flower. Three long, petal-like segments slumped to the ground. For an instant, it looked to Alaster like some sort of inverse drop pod. He realised the comparison was apt.

Genestealers came boiling out.

The staring Guardsman was dead an instant later. He was rent apart crotch to neck by a single slash of powerful claws. Red blood fountained onto the grass. The Genestealers plunged into the nearby tent.

'Skak – there's more of them!' Patreus was pointing.

Across the ridge, other borers were bursting from the ground. Shouts, screams and gunfire could be heard from everywhere.

Within moments, the orderly camp was reduced to bloody chaos.

From the western side there came an enormous explosion. Mud, grass and bodies were hurled into the air. A ball of sooty flame expanded behind them. Some panicky fire had ignited an ammo dump.

To the east some tents were already aflame. Burning figures ran helplessly from them, straight into the claws of the waiting Genestealers.

Moments later, the Space Marines plunged into the fight.

They did what they could, but it was brutal, close-quarters work. The Genestealers had the advantage of speed. They were everywhere. The Guard command structure appeared to have collapsed. There was no sign of control or direction to the masses of fleeing soldiers.

For an acid moment, Alaster wondered how many of the officers had been moustache-trimming when the attack happened.

The marines lent what assistance they could. Every moment consisted of hacking and slashing at masses of alien attackers. Hardly a second seemed to go by without the roar of a bolt pistol or the hiss-crackle of Kodos' plasma pistol. The landspeeder jumped back and forth, dumping concentrated fire into masses of bugs, then springing back from their claws.

The Space Marines started at one end of the camp and worked their way through. It was slow, bloody fighting. A Genestealer's skull cracked here, a claw dodged there. Slowly they moved through the smoke and the confusion, cutting down every alien they came across.

Whenever they passed a boring-creature, a grenade was tossed down its mouth. It was a temporary measure, but it should slow any reinforcements. On several occasions, Alaster had the satisfaction of watching a fountain of torn Tyranid remains spout from the lips of two different holes.

They fought well and they fought hard. However, it was clear from the start that this was a losing battle. Even as the Genestealers were driven back, it was clear that they were succeeding in their mission. Butchered soldiers lay everywhere, mangled guts and torn scraps of uniforms littering the ground. The Genestealers' objective had never been to survive or to take this ground. Instead, it had simply been to wreck the artillery encampment.

They had succeeded marvellously.

As well as slaughter every man they met, the Genestealers had attacked the big guns themselves. Alaster walked past a broken basilisk, flames rising from its fuel tank. Fuel had spilt everywhere. In the intense heat of the fire, the barrel was sagging. The metal had been weakened. It would never speak again.

Slowly, the marines fought their way to the other side of the camp. They managed to martial the few Guard survivors that they met, organising them into something resembling a firing line. With some support from the soldiers, they finally cleansed the last tent of the aliens.

Alaster found himself stood there, staring at the carnage all around. The ridge had gone from a tranquil grassland to a hellish scene of death. Fires rose everywhere. Thick plumes of smoke drifted into the sky. Collapsed tents were strewn around. Broken tables and chairs emerged from a few. And everywhere there was blood. Blood and death.

With his training and his conditioning, Alaster was able to face this scene of horror without total paralysis. Rather the emotional side of his mind simply shut itself down, waiting for the cues to re-emerge from its shell. He looked dispassionately at the wreckage. He would, of course, be appalled by all this later. But the time for that would be after the battle's end.

Others were not so fortunate. Nearby a young soldier, a Minorian conscript by the looks of him, was sat on the ground. His lasrifle was on the grass in front of him. The man – who was really not that much more than a boy – was crying his eyes out. Clearly the butchery around them was more than he could handle. Nearby lay the mangled corpse of a genestealer. Alaster had shot it seconds before it would have decapitated the young Guardsman. The man had heard the bang, spun round, seen the dead alien, yelped in fear and then had collapsed onto the grass.

Alaster looked at him, noting their different reactions. Just for a moment, it brought home to him just how much he'd changed, or had been changed. Just for a second he felt like more of an alien than the dead monster on the ground.

Then he shook it off and went back to work.

It was all over a few minutes later. The marines threw the remaining Guard shells into the open tunnels. Grenades were used as detonators. The resulting explosions made the tunnels collapse and cave in. The ridge found itself pockmarked with several deep, conical craters.

Still the smoke rose.

Kodos surveyed the scene. 'Well,' he said, 'that's the artillery done for.'

'Where does this leave us, Sergeant?' Alaster asked.

'Up skak lane,' Kodos replied grimly.

At that moment, Lakon's voice crackled over the public channel. 'Sergeant Kodos! What in the Emperor's name is happening over there?'

Kodos sighed. 'Nothing good, Captain. Seems the Nids had a little plan for our artillery.'

'Report. We can see a lot of smoke. And we heard shooting. What's the status of the artillery?'

'Gone. Every gun barrel's damaged. None of them look usable. And we've only got two dozen survivors from the crews.'

Lakon was silent for a moment. Then he let loose with a string of profanities. 'You did warn them, right?'

'Yes. And no-one wanted to know.'

'And they know now,' Lakon said. 'And – hang on, what the holy skak is this?' There was a pause. 'Terra's skakking fields. They're moving. The Nids are moving!'

'On the other side of the Gap?'

'That's right. Skak me, there's millions of the bastards! We're just getting satellite footage in – real-time. It looks like a carpet, flowing up the mountainside.'

'What about our forces there?'

'I'm pulling them back. We need them here – there's skak all they can do on their own against that lot.'

Sandrer looked around. Nid ichor was splashed all over his armour. 'We're screwed, aren't we?' he said in a resigned tone. He wasn't addressing anyone in particular.

'We can slow them down a bit,' Patreus said. 'That's got to count for something, right? That'll give other people time to do … something.'

'Like what, exactly?' Nasty said. 'And just in case the brain trust over there hadn't noticed – that'll be other people. Not. Us.'

'You lot,' Alaster said suddenly. 'Quit it. This isn't the time.' He'd gone from unemotional to angry horror. How could this be happening? They were about to lose! Everything had been under control this morning! How could it have changed so fast?

The landspeeder dropped in nearby. 'We heard all that,' Eirik put in grimly. 'Oh well. It'll be a saga-worthy last stand, I suppose. I'll buy you all a pint in the Emperor's Halls.'

' "The Emperor trusts that every Space Marine will do his duty",' Haakon quoted from somewhere. 'And it looks like today is the day. So be it then. I'll bring no dishonour on the Wolves.'

'Nor I,' Haakon agreed.

Alaster found his eyes tracking toward the silvery line of the river, visible through the smoke in the distance. He shook his head, trying to focus his attention on the matter at hand. This wasn't a time to go drifting off!

'Should we rush them?' Kodos suggested to Lakon. 'One big push, break their momentum?'

'That'd only work if we could catch them right at the Gap itself,' Lakon replied, 'where they're packed together. And we'd need every single marine. We can't get everyone there in time. It's a run uphill, in case you'd forgotten. No. Our only chance is to make a stand of it, here on this side of the valley.'

Alaster could see the problem. Main force had been the plan all along. And main force had just failed, spectacularly. Only it was looking like there wasn't any backup strategy.

His eyes drifted toward the river again. He found them tracking along it. He could just see the dam, before the foliage of the intervening wood obscured it.

The dam.

An idea exploded into his brain.

'-hopeless,' Kodos was saying, 'then so be it. If we must go down, we'll go down like Ravens.' He sounded determined, in a cold sort of way.

'Hang on,' Alaster said suddenly, on the public channel. 'I've got an idea.'

Kodos's eyelenses glowered at him. 'Oh do you know?'

'Wait,' Lakon's voice crackled over the earphones. 'We may as well hear it.'

'The dam – did anyone defuse the actual mines?'

Lakon hesitated. Then: 'No, Brother Raven. We haven't had time yet.'

'Then we can take the dam out.'

Haakon asked, 'How does that help?'

'Do it at just the right moment and we can drown the Nids,' Alaster said. 'That's what they were planning to do to us, wasn't it?'

There was a moment of silence. Then Lakon said, 'By the Emperor, he might be onto something!'

'It would take careful timing,' Kodos said.

'It's better than anything else we can think of,' Lakon replied. 'All right, do it. I'll spread the word to the other commanders. You need to get to the dam ASAP. Do whatever's necessary to blow those mines. But wait for my word. We need it to be when the main force is entering the valley. They need to be committed.'

'We'll take you,' Haakon said. 'The landspeeder can go faster than your packs. Climb on.'

There was only room for a few of the marines. Alaster found himself clinging to one of the wings. Patreus was hanging onto the other. Nasty and Kodos had the aeroform struts at the back. Sandrer, Fegust and Eorvan were going to have to wait.

'Okay, has everyone got a good grip?' Eirik asked.

They all had.

'All right. Here goes. For Russ and the Emperor!'

The engines whined. The sound rose. The ground dropped away. The landspeeder slammed itself forward and up. A wall of air smacked into Alaster. He could hear the roar of their passage, even through his helmet. Grimly, he clung onto the wing, even as the mighty wind tried to rip him off.

They tore through the air. He caught a glimpse of their shadow, flowing over the trees below. The dam surged toward them.

'Stop one, coming up!' Eirik shouted.

They dropped down in front of the dam. At the last moment, the landspeeder growled to a halt. The dam was literally inches in front of the bumper.

'Wow,' Nasty said. 'That was quite a ride!'

'There they are!' Patreus pointed. The mines were off to their left and down a bit. Obligingly, the Wolves dropped the landspeeder a metre or so. They were now level with the mines. The things remained every bit as bulbous and ugly as they had earlier. Their shadows stretched out over the concrete.

Alaster stared at them.

'So,' Haakon asked conversationally, 'how exactly are we going to do this?'

'I was thinking just shoot them,' Alaster said. It seemed a bit inadequate. 'They don't look too stable.'

'I think we should pull back a bit,' Eirik said. 'Use the guns on the landspeeder. A couple of rounds should do it. Then the moment we're done, we jump out.'

'Why?' Nasty asked.

'Do you want the dam landing on you?' Kodos said with sarcasm.

'Oh. I suppose not, then.'

'Yeah, you look ugly enough as it is, let alone squished under a load of falling concrete.' Patreus couldn't resist getting a quick gibe in. There was the possibility that, if this went wrong, it might be his last.

'Now we wait,' Kodos said.

A tense wait for Lakon's signal ensued. There was a brief distraction while the Wolves moved the landspeeder into position. Then the marines had to settle down and wait, or at least as best they could in mid-air.

'Here they come,' Patreus said. His head was aimed at the Gap.

Haakon whistled. 'Now there is a sight you never want to see.'

'If I was drunk,' Eirik said, 'I'd blame the beer. Pity I'm not, really.'

Something was happening up at the Gap. It looked as if some vast tsunami had crashed against the other side of the mountains and was breaking through the pass. A flood – there was no other word – of raging, alien bodies was pouring out between the peaks. It flowed over every obstacle. There was sound, too. Even from here it carried. They could faintly hear the mad chittering of the millions of blood-hungry Tyranids.

'Skak me,' Nasty said quietly.

For once, Patreus missed the obvious rejoinder. But in fairness to him, Alaster noted, they were all quite distracted.

'Ring-side seat at the end of the world,' Alaster whispered.

The surge of bugs was pouring down the hillside.

Lakon's voice crackled in their ears. 'Do it when the front reaches the river.'

They were almost there.

'Now.'

The landspeeder spun, to face the dam once more. 'Grab a hold, everyone!' Haakon roared.

An instant later, in the mid-afternoon sunshine, the heavy bolter spoke. A plume of bolts hammered into the top mine-sack. It spasmed and burst. A gelatinous, greenish fluid sprayed over the ones below.

An instant later, the potent fluid suddenly noticed the oxygen in the air around it. At that very moment, the landspeeder leapt skywards. It was as well it did as a powerful chemical reaction was beginning.

The Tyranid bio-explosive was a concentrated and highly explosive material. In the arcane language of chemistry, it was 'hypergolic' – self-igniting. It was a witch's brew of hydrogen and fluorine. It was metabolised into existence inside the mine-sacks. Their spores would be pasted in place, where they would subsequently grow. The substance their glands secreted was so unstable that it couldn't be allowed existence outside the protected confines of the sacks. The globules of explosives were surrounded by sturdy membranes, of the most neutral and corrosion-resistant materials the Nids could grow. Even the smallest knock could be enough to destabilise the foul stuff. Earlier, when he had shot out the node, Kodos had come far closer then he had realised to setting off the mines. Luckily, or perhaps by benediction of the Emperor, they still hadn't been fully-grown at that point. The way to go had been small, but it had been enough to make a difference. Their deadly chemical contents had remained inactive, on that occasion. This was just as well.

Those contents could only ever be allowed to meet oxygen once.

Beneath the landspeeder, a third sun blossomed on the dam wall. For a few moments, a nightmarish strobelight shone out over the valley. It was a blindingly clear, white-hot flash. For a few instants, the temperature of the fireball was hotter than the surfaces of Riothria's twin suns.

An enormous boom shook the air itself. The landspeeder rocked violently as the pressure wave swept past. Haakon had to fight with the controls to stop them spinning from the sky. Patreus was almost knocked clean off.

Beneath them, a great crack was opening on the dam. The concrete structure had been shocked beyond its tolerances. It groaned and rumbled. Tremors rent its structure. Chunks of grey material cracked and fragmented and fell from its sides. The first exploratory spray of water seeped through the crack. The dam gave out a vast shiver.

Then it burst.

The dam tore and ruptured like tissue paper. Its stony deathscream was heard all the way across the valley. The torrent of Nids looked up in sudden confusion.

Six billion metric tons of water were suddenly unsupported.

The Ravens and the Wolves watched from the safety of the landspeeder, high above the cascade. They watch in awe as a vast, white wall of water collapsed toward the valley. There was nothing slow or gentle about its movement. It wasn't a flow. It might be liquid but there was nothing soft about it. It was instead a hammerblow, a foaming white wall of death slamming downwards and out.

The water tore apart and crushed everything before it. It sped like an eager bullet toward the Nids. The sheer, mechanical force of the collapsed reservoir was almost beyond description. It would eventually fade, seep away into the soil and subside but for mile after mile down the valley, it would leave a trail of destruction.

There was a brief moment as the closest of the Nids looked up. The foaming wave rose above them, blocking off the light of the suns. They were plunged into its shadow. Its roar was deafening. And hungry.

It fell on them.

From the landspeeder and the encampments atop the hillside, the Space Marines watched in awe. Destruction flushed out across the valley. It was as if the planet itself was claiming vengeance for the destruction the invaders had wrought upon it.

The flood surged on, through the screeching mass of Nids. The bugs turned to try and flee, but it was too late. They couldn't outrun the angry sea as it thundered toward them. Its waves fell upon them, crushing and rending and tearing.

'Wow,' Nasty breathed.

As they watched, the eager surge was destroying the mass of Nids. A few stragglers fled back toward the Gap but it was too little, too late. The major mass of their army was vanishing under the tide.

The enemy vanquished, the water surged on. Behind it the valley was flooded. The light of twin suns gleamed on the surface of the new lake. Here and there, broken bug corpses floated in the water.

'Skak me,' Kodos said quietly. 'We've won!'