My mouth turns dry. ‘Right. I overheard Bernie and Hewett talking when we got off the bus.’

‘“Overheard”?’ Gem makes air quotes around the word.

‘Okay, I read their lips.’

Gem’s eyes narrow. The particulars of Dolphin training aren’t common knowledge outside our house. I imagine he is rewinding the last two years, wondering what else I might haveoverheard. ‘And what did they say?’

I glance at Dr Hewett, still fiddling with his control pad. Whatever he sees in his readouts, he clearly doesn’t like it.

‘Bernie mentioned “inside help”,’ I say. ‘Which means –’

‘Someone at HP sabotaged us.’ Gem is definitely biting back a curse now. ‘And if that person didn’t want to die in the attack –’

‘They would be on this bus.’

Half an hour later, we arrive at the docks where our training vessel, theVaruna, is moored.

While the other students unload the bus’s cargo bay, I pull the Dolphins aside in the parking lot: Lee-Ann, Virgil, Jack and Halimah.

‘Tá fealltóir againn,’ I tell them.

Literally, this translates asThere is a betrayer at us, which seems appropriate.

We’ve been using Irish as our internal code since the beginning of the year. Irish is so rare that the chance of anyone understanding a word we say is remote. Each class of Dolphins chooses their own language. Amelia’s learned Coptic. The juniors had Maltese. The sophomores chose Latin because they had no imagination. If you don’t have a talent for languages, you wash out of House Dolphin pretty quick.

I tell my housemates what I suspect. Sabotage. Treachery. Cold-blooded murder.

It’s a lot to take in.

Telling them is a risk. I have no idea who betrayed the school. Any of them could have done it. But I can’t start mistrusting everyone. I need their help.

Dolphins focus on communication and exploration, but we also train in espionage. I want my housemates on high alert.

Halimah Nasser looks so angry I imagine steam bubbling under her hijab. ‘How do we find the traitor? And what do we do with them?’

‘For now,’ I say, ‘just watch and listen.’

In Irish, this is ‘Bígí ag faire agus ag éisteacht.’Be at your watching and listening. Again, that sums things up pretty well.

Lee-Ann Best’s face is brick red. She’s our best at counterespionage. She probably takes this news as a personal insult. She scans the faces of our classmates, no doubt assessing each of them for the potential of betrayal. ‘I had friends in the other grades.’

‘We all did,’ Jack Wu says. He lifts one eyebrow towards Dr Hewett. ‘Ana, you have any idea why the professor assigned a Shark to you?’

The Shark in question, Gemini Twain, stands just out of earshot. He’s surveying the wharf for any sign of threats. I wish he didn’t take his bodyguard duties quite so seriously.

The docks aren’t crowded, but Gem gets some strange looks from the local fishermen. I guess it’s not every day they see a fourteen-year-old standing sentry with a military-grade assault rifle and two sidearms. Gem just nods at them politely and tells them good morning. They give him a wide berth.

‘No clue,’ I say. ‘Hopefully we’ll find out once we’re at sea.’

Virgil Esparza has been quietly staring at the crushed-shell road. Now he says, ‘He used to teach at Land Institute, you know.’

My shoulders tighten. ‘Who?’

He nods towards Dr Hewett.

I’m so stunned I can’t remember the Irish forAre you kidding me?

‘Freshmen!’ Hewett calls out. ‘Gather up!’