Kally would have liked to wake up to a happy scene of a large meal and a friendly face. Instead, she woke up to Mr D's angry cherub face glaring over her.

'Well,' he grumbled. 'Sleeping beauty's finally awake.'

Kally sat up and rubbed her head. 'What happened?'

'You blacked out.' Mr D wasted no time chatting. 'After destroying my arena, no less.'

She looked around and saw she was in some sort of infirmary. Funny – she hadn't known there was an infirmary. Then again, with all the dangerous activities here she supposed there would have to be medical services somewhere around.

'Sorry,' Kally mumbled. 'I was just trying to kill a monster dog that appeared from the Underworld.'

'"Sorry" won't fix my arena, will it Katie?' he snapped. Someone was grouchy.

'Once again, my name is Kally,' she said.

'Whatever.' Mr D turned around to pour himself a glass of water from a jug sitting on a bedside table.

'Run out of diet Coke?' Kally asked sarcastically, sliding off the bed.

Mr D sneered. 'No,' and the water swirled into a darker colour. She didn't need to drink it to know it was Mr D's preferred beverage.

'Now,' he said, suddenly all business. 'As much as I would like to send you to the harpies for kitchen duties forever, there's a council meeting going on and they want you there.'

'What do they want me for?' Kally peered in a nearby mirror and winced at the scrapes and bruises all over her body.

'What do you think I am? The Oracle?' Mr D said. 'How should I know, Kristy?'

'It's still Kally.'

'Whatever!' Mr D looked close to a breakdown so she decided not to push it. 'Just get to the rec room. They're waiting for you.'

When Kally entered the rec room, she decided Dionysus had been lying. They hadn't waited for her. A full scale argument was going on, and Kally had stepped right into the middle of it.

The rec room was unusually full of demigods convening around the ping pong table. She spotted Annabeth and Percy right beside each other, hands interlocked. Chiron stood behind them, arms folded across his chest, a concentrated expression on his face.

A group of about seventeen others stood around the ping pong table too. Clarisse looked like she was about to leap across the table and stab a pretty Asian girl who seemed to be yelling at Clarisse.

'How do you know?' the Asian girl demanded. 'He could be the traitor! He turned on us before, why wouldn't he do it again?'

Connor Stoll interrupted. 'Because Chris isn't the same person he was then. He was angry and brainwashed. He's changed.'

'What Stoll said,' Clarisse growled.

A tall, dark-skinned girl with burn scars all over her fingers and dressed in overalls pointed her finger at Kally. 'I still say it was her!'

Chiron raised a palm in a gesture of peace. 'Nyssa, you have no proof and no reason to distrust Kally.'

'We don't know anything about her!' The girl, Nyssa, cried. She slammed her fist on the ping pong table. 'We don't even know who her parent is. We can't trust her.'

Nyssa's eyes burned with rage as she glared at Kally. She turned back to Chiron. 'We must act! We have to get rid of her.'

'No.' Pollux stood. 'Chiron's right Nyssa. You don't have any proof. Kally's done nothing wrong.'

'Oh of course you defend her,' a small girl with dark hair pulled into a high ponytail retorted. 'Can't have your girlfriend being sent away from camp now, can you?'

Annabeth threw her dagger into the table, enraged. 'His life is none of your business Lou Ellen. Leave it alone.'

'Why are you defending him?' Lou Ellen asked. 'You're just as bad. You don't talk to him any more than the rest of us.'

'I'm defending him because he's done nothing wrong and he doesn't deserve to be picked on.' Annabeth snapped. 'He fought bravely today. Anybody who thinks otherwise can take it up with me.'

The campers were quiet for a moment. No one dared argue with Annabeth staring everyone down, her grey eyes steely cold.

Chiron cleared his throat. 'All these arguments are valid. However, we cannot let suspicion tear our camp apart.'

'Not being suspicious almost got camp torn apart by a monster today,' Clarisse pointed out. 'We have to make sure of our suspects.'

'Suspects for what?' Kally asked. All eyes turned on her. Some were resentful, some were apologetic. Others were just plain bored.

'For letting Orthrus into the camp, genius.' It was Rachel who spoke. She shouldered her way through the crowded room until she was right in front of Kally. 'The magical border around the camp keeps monsters away. Someone had to have let that thing in from inside the camp.'

'So there's a traitor in camp?' Rachel nodded.

That sounded familiar. Of course! Annabeth had said the same thing earlier when they were battling Orthus.

'And you suspect me?' she asked.

Rachel's green eyes didn't move from Kally's face. Slowly, about half of the demigods in the room nodded their heads. She noticed Clarisse nodding too.

'Nobody here trusts me.' Kally said.

'That's not true,' Annabeth said immediately. Percy nodded in agreement, along with Pollux. She looked around for Nico, but he was nowhere to be seen.

Chiron laid a gentle hand on Kally's shoulder. 'We have no reason to distrust you. Some here are simply more aware of the risks-'

'-the risks that a stranger can bring to camp with them,' Nyssa finished for him. Her dark eyes still did not waver from Kally's.

Kally decided to ignore the tension towards her and focus instead on something that had been bothering her since she came in.

'Why is Chris a suspect?' she asked.

Everybody in the room went quiet. Kally strongly suspected it was due to the withering glare Clarisse was giving them.

But the Asian girl spoke up. She didn't seem afraid of Clarisse's wrath like everybody else. In fact, she seemed confident; like she knew she would get her way. 'Because he's turned traitor before. During the Titan war last summer, he was part of the Titan's army.'

'Until Clarisse rescued him from the Labyrinth,' Annabeth said firmly but quietly. 'He wasn't evil Drew, and he isn't any more evil now.'

Drew scoffed. 'Please. I don't have any sympathy for him. Just because he went crazy doesn't excuse what he did. Just like dying didn't excuse what that Silena did.'

The crowd immediately fell silent. Barely a whisper of breath could be heard. Clarisse tightened her grip on her sword, and Kally could see Annabeth grinding her teeth from across the room.

Surprisingly, it was Percy who spoke up. 'Silena Beauregard died a hero. She gave her life for the war and for this camp.'

'She was spying on us for Kronos the whole time!' Drew insisted. 'She was a liar and a traitor and I'm ashamed to say I knew her.'

Clarisse snapped. Several pairs of hands had to hold her back from crawling across the table and putting her sword right through Drew's head. All the while Clarisse kept screaming, 'She was a hero! She died for you! How dare you say that about her! You coward, come over here and face me!'

Eventually, Chiron had to remove Clarisse from the room to prevent injury to herself and others.

Drew didn't look one bit regretful of what she'd said. She only looked more confident. 'You see? She manipulated people to get what she wanted. She manipulated Clarisse, and if our strongest warrior can be manipulated then what good are we?'

To Kally's complete surprise, people began nodding and murmuring agreement.

Drew kept speaking. 'We are weak. We didn't even see another spy slip into our borders. And I'm willing to bet it was Chris.'

Annabeth looked outraged and like she wanted to argue, but her mouth stayed closed.

'How else would they have slipped past everyone?' Drew reasoned. 'By being the one person no one would suspect again. Mr Crazy himself.'

For a brief moment, Kally found herself believing whatever it was Drew was saying. Chris had to be the traitor. It was only logical.

But then she remembered who Chris was. He was her friend. They hadn't spoken in weeks, and he was mad at her, but he was still her friend.

'Listen here,' Kally said curtly. 'I don't know what you think you know, but I know Chris. He's a good guy. He may have done stuff in the past that I'm sure he regrets. But in the present… He's our friend. And call me old fashioned, but I don't turn my back on friends.'

Drew seemed shocked that anyone dared talk back to her. Everyone else seemed to snap out of a haze. They blinked a few times and nodded. Drew looked like she was about to say something snarky in reply, but Chiron trotted in and saved the day.

'The question now,' he said thoughtfully, 'is what to do next. We can't go around suspecting everyone we see. We'd tear ourselves apart.'

'I suggest a quest,' Lou Ellen spoke up. 'To find whoever is responsible for letting the monster in, and why.'

There were noises of general agreement and Chiron sighed. 'It seems the only way to get some peace of mind. Rachel?'

Rachel stepped forwards, a look of nervousness on her face. Kally had a sudden thought.

'Wait!' she said. 'Nico isn't here. Shouldn't he be part of this? I mean, he did fight Orthus with us. He should be here.'

'I'm afraid Mr di Angelo is unable to be here,' Chiron told her. 'He used a great deal of power earlier, and has not yet recovered from his fainting spell.'

Kally frowned. She must have missed him in the infirmary. 'It should be his quest.'

'And why is that?' Drew questioned.

'Because,' Kally snapped. 'He was so brave in that fight. He used up so much power to help. And he passed out from the effort of moving that enormous boulder that pushed Orthus right back to Tartarus.'

Percy and Chiron exchanged a look. Percy spoke this time. 'Nico passed out before that boulder moved anywhere. Besides, he barely had the energy to stand, let alone move a ten tonne rock.'

'But… he moved it.' Kally stammered. 'I saw it. The boulder moved-'

'It moved, yes.' Annabeth interrupted. 'But we have no idea how. Everyone was exhausted, Nico especially. As far as we know he's the only person at camp with geokinetic abilities…'

'Wait, geokinesis?' Kally repeated. 'What's that?'

'Being able to move and control the earth with your mind,' Annabeth explained. 'As far as we know only children of Hades have the ability because of his domain beneath the earth. But we only have one child of Hades, and he was unconscious when it happened.'

So how did it move then? Kally wanted to ask again. She knew she would only get the same answer.

At that moment, Nico walked through the door of the rec room. Well, stumbled through might have been a better adjective. He held a hand to his head and another to the wall for support. A bandage was wrapped around his head like some sort of cap, and he had a slight limp.

He looked up and met the eyes of twenty demigods, a centaur and an Oracle, all staring at him. 'Hi guys. Didn't mean to crash your party.'

'Not at all Nico,' Chiron replied happily. 'We were just discussing you.'

'You were?' he asked. The shadows around his eyes seemed to get darker. 'Why?'

'We're putting together a quest,' Annabeth said. 'To find out who the traitor in camp is.'

'So why do you need me?' Nico asked again. He slumped down into a chair.

'Well…' Annabeth seemed at a loss for words. A first, Kally was sure.

'I suggested you lead the quest.' Kally told him.

He stared at her. 'Why?'

She listed off the reasons she had mentioned before, and managed to add in one or two more to persuade him. He still looked unconvinced.

'I've never been on a quest before,' he said quietly. 'I don't know the first thing about it. Send Percy, or someone else with some experience.'

'Actually Nico,' Chiron smiled warmly, 'I think Miss Anastas is right. I think you should lead this quest.'

Nico held eye contact with Chiron for a while. It seemed like he was internally debating whether or not to accept. After a moment, he slouched his shoulders and nodded in defeat.

'Excellent.' Chiron beamed. He addressed all the remaining demigods. 'Now everyone, I must thank you all for coming. But unfortunately you must leave. I'm sure this is keeping you from beloved activities and such things. You understand. Thank you.'

They waited until the last demigod filed out so that it was only Chiron, Nico, Annabeth, Percy, Rachel and Kally left in the room.

Rachel sat down in front of Nico. It was easy to see they both felt awkward facing each other.

'So um…' Nico cleared his throat. 'How does this… work… exactly?'

'You ask me a direct question and I'll spurt out a prophecy,' Rachel said.

'Okay…' Nico drew a deep breath. 'Um… Oracle, can you tell me about my quest?'

For half a second, nothing happened.

Then Rachel's eyes became pale green and began to glow. A slightly greenish haze spilled out from her mouth when she opened it, and when she spoke it was like three raspy voices instead of one.

'A hero must face their threatening king,

Balance and peace to the gods he may bring.

A treacherous scheme begins to unravel,

Families lost reunited in travel.

A friend to be lost, an enemy gained,

True loyalties proven and love ascertained.'

Rachel's eyes fluttered shut and she slumped in her chair. Percy caught her shoulders before she could fall out. When she reopened her eyes, they were back to their regular green.

'W-what happened?' she wondered. 'Did it work? What did I say?'

Slowly, Annabeth repeated the prophecy to Rachel. She shrugged when asked what it meant. 'I don't know how to make sense of them. I just happen to be the messenger.'

'True loyalties proven,' Annabeth muttered. 'That could be the traitor. Someone we think we can trust shows us we can't.'

'It is a possibility.' Chiron stroked his beard in thought. Then he clapped once and looked down at us. 'But we mustn't dwell on it. It's very nearly time for dinner. You'd better go.'

After dinner at the pavilion, Kally paced back and forth by her bunk. She couldn't decipher the meaning of the prophecy.

Percy had told her not to worry about it too much. 'Prophecies will come true, whether we like it or not. The meanings will become clear eventually.'

She didn't even know why she was so obsessed with it. It wasn't her prophecy or her quest. It was Nico's. It was likely that none of the passage even applied to her.

She flung herself onto her bed in frustration. Travis Stoll wandered up beside her. Kally groaned inwardly.

'Hey,' he said, his usual grin firmly in place. 'Have you seen the arena?'

'Not since I blacked out,' Kally told him. She remembered Mr D complaining about the state of it. 'How bad is it?'

'It's pretty wrecked,' he said, running a hand through his hair. 'Chiron reckons we won't be able to train there for at least a month.'

'That's pretty bad,' Kally agreed.

Travis smiled again. 'That crack in the ground's still there though. It's huge. I wonder who even made that thing. And how in Zeus's name are they gonna fix it?'

Kally wondered the same thing. She was worried about more monsters climbing up out of the Underworld to attack. She shook off the thought.

'I might go have a look.' She stood and grabbed her jacket, putting her arms through the holes.

'Great, I'll come,' Travis grinned. He started after her but she stopped him.

'I think I'll go alone,' she said. 'Sorry Trav.'

He pretended to be wounded. 'Ouch, that hurt.'

'I'll be back later tonight, okay?' she said, walking further out the door. 'Cover for me if the harpies come around.'

The arena wasn't far. Five minutes later she was standing at the entrance. She plucked up her courage and slipped under the gate.

Travis wasn't exaggerating. The mess was everywhere. Broken slabs of stone were strewn about the place, and bronze weapons were scattered around too. The rocks that Nico had thrown with his power were rolled away from the crack into a neat pile.

The crack itself was enormous. There was no way they could just fill it up with dirt or something. And they couldn't just pave stone over the top.

Kally wondered again just how that huge boulder had moved across the arena and taken out Orthus.

She thought about the battle. It couldn't have been Nico; he was unconscious, and so was Annabeth.

Rachel had some pretty cool power, but Kally doubted she could move rocks.

Pollux was exhausted, and rocks were hardly in his domain.

And Percy was trapped under Mrs O'Leary. Even if he had the ability to move rocks he would have been useless with his arms pinned below ground.

That left only one person.

Kally stared at her open palms, hardly daring to believe. Then she touched them lightly to the earth. She felt a cold chill run through her bones and a lifeless hum that she couldn't place.

She stared at the crack in the ground. She concentrated all her willpower on the pit. She saw it closing in her mind's eye. She saw the gap becoming smaller and smaller until it appeared to be just a thin line trailing the original path.

And slowly, miraculously, the earth really began to move. It rumbled beneath her feet as the two halves were forced together. In only minutes, the gap had sealed itself completely, like it had never even existed.

Kally took her hand away from the dirt in shock. She stared once again at her palm.

Suddenly she felt drained, like she'd just run a mile up a hill. She stumbled slightly but caught herself. Her head spun.

'It was you.'

The voice caught her off guard. She turned to the entrance gate to see Nico stepping out of the shadows. He was staring at the ground where the chasm used to be.

'You moved that boulder.' He said.

Kally nodded nervously. 'I… I think so.'

'How?' He narrowed his eyes at her. 'I don't understand. I thought I was the only one who could-'

He stopped mid-sentence. She looked to his face and saw him staring at the air above her head. 'What are you looking at?'

She looked up to see a blazing black mark above her head in the shape of a helmet.

She looked back at Nico's dumbstruck face. As the symbol faded he slowly moved his gaze down to her eyes.

'The mark of Hades,' he said quietly. His voice was so eerily smooth; it didn't disturb the absolute stillness of the night.

'What does that mean?' Kally asked.

'It means you've been claimed by your godly parent.' He said. His eyes still locked on hers, he said, 'You're a child of Hades. You're… my sister.'