"There they are." Grover nodded towards a couple of younger kids arguing in the bleachers. "Bianca and Nico di Angelo."

The girl wore a floppy green cap, like she was trying to hide her face. The boy was obviously her little brother. They both had dark silky hair and olive skin, and they used their hands a lot as they talked. The boy was shuffling some kind of trading cards. His sister seemed to be scolding him about something. She kept looking around like she sensed something was wrong.

Annabeth said, "Do they . . . I mean, have you told them?"

Grover shook his head. "You know how it is. That...

The good news: the left tunnel was straight with no side exits, twists or turns. The bad news: it was a dead end. After sprinting a hundred metres, we ran into an enormous boulder that completely blocked our path. Behind us, the sounds of dragging footsteps and heavy breathing echoed down the corridor. Something – definitely not human – was on our tail.

'Tyson,' I said, 'can you –'

'Yes!' He slammed his shoulder against the rock so hard the whole tunnel shook. Dust trickled from the stone ceiling.

'Hurry!' Grover said. 'Don't bring the roof down, but hurry!'

The boulder finally gave way with...

… Mrs. Dodds turned on me. There was a triumphant fire in her eyes, as if I’d done something she’d been waiting for all semester. ‘Now, honey –’

‘I know,’ I grumbled. ‘A month erasing textbooks.’

That wasn’t the right thing to say.

‘Come with me,’ Mrs. Dodds said.

‘Wait!’ Grover yelped. ‘It was me. I pushed her.’

I stared at him, stunned. I couldn’t believe he was trying to cover for me. Mrs. Dodds scared Grover to death.

She glared at him so hard his whiskery chin trembled.

‘I don’t think so, Mr. Underwood,’ she said.

‘But –’

‘You – will – stay...

When we got to the gym, Coach Nunley was sitting at his little desk reading Sports Illustrated. Nunley was about a million years old, with bifocals and no teeth and a greasy wave of grey hair. He reminded me of the Oracle at Camp Half-Blood – which was a shrivelled-up mummy – except Coach Nunley moved a lot less and he never billowed green smoke. Well, at least no that I’d observed.

Matt Sloan said, ‘Coach, can I be captain?’

‘Eh?’ Coach Nunley looked up from his magazine. ‘Yeah,’ he mumbled. ‘Mm-hmm.’

Sloan grinned and took charge of picking. He made me the other team’s...