It surprised Amelia how long the descent took. Crescentia was, she knew, vast - some hundreds of feet thick even away from the central section towards the narrower tips - and the elevator was setting a fairly leisurely pace as it moved through the interior. Occasionally it passed by a gap in the colossal station's structure, enabling vertiginous views of the inner decks across odd hollow voids, or even open gaps that led into the etherium beyond. Now and then the attendant would announce a halt, the elevator would judder to a stop and the doors would open to allow an exchange of passengers, but there were fewer and fewer people getting on as it went deeper. Nobody lived on the inside of Crescentia, the space instead being dedicated to storage and machinery. Enormous underground warehouses sprawled for acres under the residential and working districts above, piled high with crates and barrels and as busy as an anthill with activity, or there were large underground silos of ores and grains waiting to be scooped up by cranes and conveyor belts to be deposited into the hungry holds of bulk carrier ships.

Deeper still were the machinery decks, where lived the great engines that kept Crescentia alive - the water storage, distribution and purification systems with their great metal tanks and miles of pipework, the solar-powered electricity generators that hummed away in red-lit caverns, huge heat exchanges and fans to drive the air circulation system, and banks of the multiple-redundant gravity turbines that towered several storeys high, dwarfing the one on the Legacy's main deck and bathing their chambers in their eerie purple glow. It was humbling to think that, every time she'd set foot on Crescentia, her life had been so utterly reliant on all this machinery, working patiently and tireless away under her feet. It was also humbling to think of the scale of the disaster that would unfold if it ever broke down - a reminder of the precariousness of life in space, even in a port as apparently solid and enduring as Crescentia.

A chime broke into her reverie as the robot attendant spoke again: "All Passengers Prepare For Null Gravity Passage."

Amelia rechecked her feet in the floor straps and tightened her grip on the roof strap. Zero gravity was not unfamiliar to her, but it was normally something experienced only in emergency training drills. Voluntarily undergoing it was a strange experience, and she swallowed as she felt her body lightening. The elevator slowed as it passed below the gravity turbines into the zero-g area in the heart of the station, and Amelia felt a brief moment of alarm as she saw the floor beginning to tilt before she realised what it was doing - rotating through 180 degrees, like a flipped coin, turning the downward descent from the daylight side of Crescentia into an upward climb towards the Nightside. Knowing that didn't necessarily make the sight of it any easier to bear, and it was with some relief that she felt herself growing heavier again, feet once more pressing into the floor, as the elevator passed into the gravitational field on the other side of the spaceport. She exhaled a sigh and relaxed her grip as the environment returned to normal and they began ascending towards their destination. The machinery decks here were essentially identical to the ones she had already passed, but there were far more dark voids above them, empty warehouses, vacant spaces either abandoned or not yet built. The ore silos here were similar, yawning hollows like sockets for giant teeth, awaiting the bonanza of mineral wealth from Montressor that had never eventuated. The elevator moved past them all without stopping.

"Now Arriving. Surface. Nightside. C-District." The robot's head rotated again. "Please Wait For Doors To Open Before Disembarking."

The elevator rose, slowed and came to a halt in the base of a tower that was essentially identical to the one Amelia had departed from. But it was dimmer, dingier, only one ticket window was open and the posters on the walls extolling the virtues of the CPA and the importance of occupational health, safety and security were older and peeling in places. Stepping outside, Amelia looked up into a dark, starry sky over a street lit by lanterns. It was hard to believe that it was still daytime and she'd begun her journey in the clear light of the morning sun. And it was a near-empty sky as well, with the far ends of the spaceport curving away rather than overhead. A few ships were visible, approaching or departing, but most of the port's ceaseless traffic was concentrated on the other side, which felt a lot further away than even the long elevator ride suggested it was. Despite herself, she shivered. Then she glanced at the address paper one last time, looked around to get her bearings, and set off into the twilit streets.

The main building of the base hospital was a busy place even at normal times, and especially so when the shifts changed. Ko stepped into the atrium and gathered her bearings. Normally she attended the hospital once a fortnight for her back injury to be assessed, a job which Gray almost invariably took upon herself personally. But there was another medical officer whom Ko had seen speak with Gray, and the two seemed to get along - or rather, got along more than Gray normally did with her white-coated colleagues, many of whom she seemed to think were better suited to handling mops than medicine. Eventually spotted who she was looking for – a small woman with blue hair and silver tattoos, strikingly contrasting with her tanned skin – and hurried towards her.

"Excuse me, Lieutenant-Commander Rocca, ma'am?"

The medical officer turned to look at her, fixing her with sharp golden eyes. "Yes, sergeant-major?"

"I've got a request, ma'am." Ko swallowed, aware that what she was doing was both unusual by protocol and likely to arouse Gray's irritation if she ever found out. "I'm a…colleague of Lieutenant-Commander Gray's…"

"Yes, I know. I've seen you in here for your spinal examinations." Rocca nodded. "What can I do for you?"

Ko swallowed. "Well, it's about Dr Gray..."

Rocca's eyebrow went up. "What about her?"

Ko glanced around. "I'm...a little concerned about her, ma'am. She's been working overtime lately."

"Overtime?" Rocca frowned. "I don't think she has. We haven't been unusually busy."

"No, I mean..." Ko grimaced and wished she was better at this. "Things have been keeping her busy outside work. Captain Amelia's ship is in port and she asked her to help her with some...medical matters."

Rocca looked at her levelly. "I see...go on."

"And, well...I'm hoping it doesn't come to affect her in her duty here, ma'am."

Roccas gold eyes searched Ko's pale blue ones. For a moment, they held each other's gaze. Then Rocca gave a smile - not of happiness but rather of vindication, as if something she'd suspected had been confirmed.

"I knew it... what's she been getting into?"

Ko blinked in surprise. "Ma'am?"

"Our mutual friend isn't always as opaque as she tries to be." Rocca smiled again, this time with humour. "Come up to my office, sergeant major. Tell me what I need to know."

Ko followed her up the stairs, through a door marked PRIVATE and into a warren of small corridors and smaller rooms until they reached one that seemed indistinguishable from all the others. With the door firmly closed, Rocca sat at her desk and listened while Ko explained as much of the situation as she felt able to. When she finished, Rocca sat back.

"No wonder she wanted to run some toxicology tests. Right. What do you want me to do?"

Ko was mildly surprised - she'd been expecting to have to defend the private endeavour that Gray had become involved in, but if Rocca had any doubts about that, she wasn't airing them now.

"Um, well..." Ko cleared her throat. "I'd be grateful if you could just...keep an eye on her. Make sure nothing happens."

"You're worried for her safety?"

"Not so much when she's on base, ma'am, but the rest of the time..." Ko grimaced. "Not that you could do much, but... please, keep an eye on her as best you can. Try to make sure she doesn't take on too much."

"We're talking about Dr Gray, aren't we?" Rocca smiled.

Ko grinned. "Yeah, I know. But...I'd be grateful if you could. Because I won't have the chance if I'm planetside babysitting this civvy of Amelia's."

"I'll do what I can," Rocca promised. "Gray is an invaluable member of the medical staff."

"But... this all has to be kept unofficial," Ko emphasised. "What Amelia is doing, what Dr Gray is helping her with. All of it."

Rocca narrowed her eyes pointedly. "My confidentiality is assured, sergeant major. You don't need to tell me twice."

"Then...thank you, ma'am." Ko gave a little smile. "That's a weight off my mind."

"Good." Rocca sat back. "Then is there anything further? Do you need anything for your stay on Montressor?"

"No, ma'am. Gray made sure I have everything I need."

"I'm sure she did." Rocca stood up, nodding in a businesslike manner. "Well, if there's nothing further, sergeant-major?"

"Right, ma'am. Thanks for your time." Ko stood up and collected her cane. At least, she thought, there's someone looking out for her…

Nightside was, architecturally, more or less a copy of the daylight side, which only made the experience seem even more surreal to Amelia, as if she had stepped through a looking glass and was now looking at the world from the other side. The streets and timber-framed buildings were nearly identical, though far less crowded with people and commerce, and despite the low lighting the place was in visibly poorer condition. People often sat or stood around in groups, and even those with places to go and tasks to do seemed to move in a listless half-shuffle rather than with the purposeful energy on the other side of the station. Robots were more in evidence as well - or was that simply because there were fewer people? - and more than once Amelia saw a tracked autoconstable cruising the streets, headlamp eyes glowing and casting circles of bright yellow light onto anything their scanning heads focused on. The people stepped out of the way to avoid them, averting their gazes.

The more she walked and observed, the more she began to feel somewhat more accustomed to her surroundings. She had to consciously alter her posture and her movements, her normal confident upright stride traded for a slower, shoulder-drooping gait that was more in keeping with the way the Nightsiders themselves moved. Whether it would help her blend in or not, she couldn't tell, and she still felt very much out of place. Nothing in her upbringing or training had prepared her for this, and part of her wished that she had brought Ko along for some advice. But then she knew that what she'd asked her old friend for was far more important than this. She would have to look after herself.

Following the street signs on the corners at major intersections eventually led her towards K-District, and she set about finding the specific address on the piece of paper she had in her pocket. K-District turned out to be an area of warehouses, blocky buildings that sat oppressively, overshadowing the smaller commercial and residential structures that had been squeezed in around them. Walking past one, Amelia caught a glimpse of something painted above a side door - gang sign, she recognised, the same one as on the paper she carried. Looking around more, she realised that she had seen other, similar signs on her journey here. Ko had been right, it seemed. Whoever the traffickers were, they clearly had quite a presence here.

8342/32 Street was on a four-cornered intersection near the edge of K-District. Two of the corners were occupied by warehouses and a third was nominally a vacant lot though the building there had been only partially demolished. The last was occupied by a ramble of tenements that somehow gave the impression of having been built at separate times despite being part of the same structure. She scanned its windows as she passed it, her instinct telling her that - though she couldn't see anything to confirm it - she was being watched. There were fewer people here, but even so she felt that this was not a place where she could just stop and observe things without being questioned. A few people sat or stood around outside front doors, ostensibly paying her little attention, though she was sure that heads turned and eyes followed her out of more than just curiosity.

A cart pulled by a couple of bullyadous rumbled past - on actual wheels, not solar-powered anti-gravity lifters. Amelia glanced at it, noting the cargo of barrels visible over the edge but not seeing anything inherently incriminating. The driver didn't give her a second look, though a rangy man perched on the rear of the cart watched her until they turned a corner and were out of sight. She wondered if that had simply been for the novelty of her, or if they had been part of the surveillance network too.

Crossing the road, she passed the warehouse the cart seemed to have come from, a large set of double-doors still open to the street. Inside, racks of barrels were stacked high and a couple of workers were mopping up a puddle - Amelia's sensitive feline nose twitched as she picked up the scent of beer, cheap and none too fresh. As she passed, she heard the harsh voice of an overseer calling out to the workers.

"Oi! What's gone on there? You didn't bloody drop one off the cart, did you?"

"Sprung a leak, boss! It's those cheap bungs. The cork's rotten."

"Then you'd better check 'em all once you're done, hadn't you?"

A sign above the door, illuminated weakly by a row of lanterns, displayed the name E.J. WHITLEY & SONS, a name Amelia carefully took note of as she moved on. Loitering was too likely to draw attention to herself, though, and she wasn't entirely certain what she should look for. It was probably too much to expect that she'd just stumble across irrefutable evidence of criminality in her first look, she reminded herself, because any half-clever gang would be sure to disguise its more nefarious activities in the same way that a corrupt ship's purser never openly flaunted their fraud. But there had to be some kind of records relating to the warehouse and its owners in the archives of the Crescentia Port Authority, and that seemed like a good place to start. She would have to pay Mr Mott a visit...and come up with some kind of plausible explanation for her interest.

Doppler had been waiting for the sharp knock on the door, but it still startled him a little when it came just before midday. He hurried down the corridor towards the front door, pausing to check his reflection in a mirror hanging on the wall. Meeting new people for the first time always made him nervous, and the fact that this was not the first time but rather a second following what he feared was a poor first impression did not help. After straightening his ascot and collar in the mirror, he turned away and went to open the door, putting on what he hoped was a welcoming smile.

"H-hello again, sergeant-major. It's good to see you again."

Ko looked up at him and raised an eyebrow. She was wearing some battered old civilian clothes, and had a small canvas seabag slung over her shoulder. Doppler's smile did not survive contact with her ice-blue gaze.

"Is it?" she said.

"I, um…" Doppler hesitated, torn between politeness and honestly. "Well, anyway, you should come in. Here, let me take your bag."

"I can manage fine, doc, thanks." Ko stepped across the threshold and watched as he shut the door behind her, paying what he thought was an odd amount of attention to the lock and latch. "I appreciate you putting me up like this."

"Yes, well, I'm always happy to help a friend of Amelia's," Doppler tried smiling again. "Your room is just down the hallway here. On the left."

Ko followed him, her eyes darting around, taking in details she had overlooked before. "Yours is upstairs, I assume?"

"Yes, that's right. But if you need anything during the night, you can just ring the servant's bell. I'll show you where the switch is." Doppler nodded.

"Servants? I thought it was just you living here."

"Well, yes, it is. I mean, I have a housekeeper who comes by every second day to clean and cook and things like that, but they don't stay here." Doppler pushed open the door to the guestroom and gestured for Ko to step past him. "But the bells ring all over the house, so I'll be able to hear it."

"I'm sure I can manage by myself. And you know the housekeeper pretty well?" Ko entered the room and dropped her seabag at the foot of the bed.

Doppler blinked, taken by surprise by the apparent interrogation. "What, old Mrs Dunwoody? Oh, well, yes, I suppose so. I mean, I've employed her for years. Ever since Sarah Hawkins left to establish her inn. Sarah's the mother of Jim Hawkins, you know, who was the boy who found the map that Amelia and I used to get to Treasure Planet…"

Ko looked around at him, her face immobile. "So you know her. Good.."

Doppler coughed, becoming awkwardly aware that he was in danger of rambling and not wanting to say anything that might invite any more pointed questions from his guest. "Anyway. Is there anything you need? Could I make you a cup of tea? Though you prefer coffee, don't you? Or maybe a sweet cocoa?"

"I'm alright, doc, thanks." Ko nodded. "But I wouldn't mind a tour around the place if you could spare some time."

"A tour? Oh, right. Of course. Whenever you're ready." Doppler agreed. "And, um...should I keep calling you 'Sergeant-Major Ko'? I don't really know the protocol..."

"Only my superiors have to call me 'sergeant-major,'" said Ko. "So you don't."

Doppler hesitated, wondering if there'd been a veiled insult in that statement. "So...just what should I call you? I imagine that 'sarge' is not acceptable from a civilian."

"You imagine right," Ko nodded, approvingly noting his concern to treat her with respect. "Just my name is fine."

"Very well." Doppler grinned nervously. "So...and that would be? I don't think I caught it before when you were here with Dr Gray."

There was a pointed pause.

"My name is Ko," said Ko, as if explaining something to a particularly slow-witted recruit.

"Ah. Of course." Doppler coughed. "Well...Ko...would you like that tour now?"

"The sooner the better," said Ko, picking up her cane. "Let's go."

"So this is the living room." Doppler waved an arm around the space. "The kitchen is just through there. Help yourself if you want anything, otherwise you're welcome to eat with me. There's a bathroom just across the hall from your room. So everything you'll need is here on the ground floor and you won't need to go up the stairs. I know you have to look after your back and everything."

"How many entrances are there on this level?" Ko looked around the room.

"Oh, three. The front, which you came in. There's an old servant's entrance around the side. And the kitchen entrance as well. But you can just use the front to come and go if you need to."

Ko nodded, taking in the room. "Do those windows open?"

"What?" Doppler looked at the tall semicircle of windows looking out over the canyon below. "Oh, no. No, they're fixed shut."

"Is there any way to access them from the outside?"

"Well, yes, there's a sort of metal walkway below them. For maintenance, I suppose. But nobody ever uses it." Doppler frowned.

"Good." Ko's eyes alighted on the fireplace. "What's that there, on the mantel?"

"Hmm?" Doppler looked. "Oh, that sword? It's Amelia's. She said she was tired of carrying it around with her on the Legacy and so I said I could take it for safekeeping."

Ko ran her eyes over it, recognising the crest on the pommel. It was a Queen's Sword, the prize traditionally given out by the Academy to the highest-performing cadet in every graduating class. She hadn't known that Amelia had won the award, but wasn't entirely surprised either, though she was curious that she had entrusted such a coveted artefact to the keeping of this canid. Amelia's regard for him obviously ran deeper than she'd thought, and she glanced sideways at him with a growing sense of respect.

"So I see," she said.

"And I suppose it's nice to have something of hers around the house." Doppler smiled awkwardly. "I mean...I don't get to see her much, what with her always being in space, so...having that there, where I can look at it every night...it helps."

"I...can imagine," said Ko.

Doppler cleared his throat. "Anyway, that's probably not of much interest to you. Did you want to see any of the upstairs? I know you won't be up there much, but if you were curious…"

"I suppose it couldn't hurt," Ko nodded. "I'll make it up the stairs, don't worry. You said you slept up there?"

"Yes, that's right. The master bedroom is there. Right above us now, in fact, so it looks out over the canyon as well." Doppler waved towards the windows. "There's also my private study up there, and the library. And a few other rooms that I don't really use very often."

"It's an impressive place you've got here, doc, that's for sure," said Ko.

"Oh, well, yes, thank you. Not that I can take credit for building it. It's been my family's home for generations," Doppler shrugged. "I just made a few modifications here and there for my astronomical studies. Which reminds me, I should show you the observatory."

"I'd appreciate that." Ko followed him. "So...does the Captain stay here often?"

"Whenever she's coming through Crescentia these days," said Doppler. "Which is fortunately often...though not as often as would be ideal. I would never ask her not to go spacing, of course, and you know she'd never stop. But still...I won't deny that I miss her when she's not here."

Ko nodded slowly. "Do you worry about her?"

"Of course. Spacing's a dangerous job. Not that I need to tell you that," Doppler added quickly. "And I know that there's nobody who's better at it than Amelia. She always comes back safe and sound. But still...every time she sails could be the last time I see her, even though I'm sure she doesn't take any unnecessary risks."

Ko nodded again, acutely aware of the risks that Amelia was currently taking and feeling uncharacteristically awkward at not being able to tell her host about it. She trusted Amelia implicitly - months spent together under fire would do that - and she'd be the first person to admit that she was not the best at interpersonal skills. But she found herself increasingly uncomfortable with this assignment and the need to keep deceiving this canid. Not for the first time, though, Ko pushed her doubts aside, focused her mind back onto her mission, and went back to work.