Dev produces his squid. Socrates snaps it up and swallows it whole. Dev grins at me, a bubble escaping from his lips. His expression saysHa-ha, the dolphin likes me best.

I offer Socrates my squid. He’s only too happy to have seconds. He lets me scratch his head, which is as smooth and taut as a water balloon, then rub his pectoral fins. (Dolphins are suckers for pectoral-fin rubs.)

Then he does something I’m not expecting. He bucks, pushing my hand up with his rostrum in a gesture I’ve come to read asLet’s go!orHurry!He veers and swims off, the wake from his tail buffeting my face.

I watch until he disappears into the gloom. I wait for him to circle back. He doesn’t.

I don’t understand.

Usually he doesn’t eat and run. He likes to hang out. Dolphins are naturally social. Most days, he’ll follow us to the surface and leap over our heads, or play hide-and-seek, or pepper us withsqueaks and clicks that sound like questions. That’s why we call him Socrates. He never gives answers – just asks questions.

But today he seemed agitated … almost worried.

At the edge of my vision, the blue lights of the security grid stretch across the mouth of the bay – a glowing diamond pattern I’ve grown used to over the last two years. As I watch, the lights wink out, then flicker back on. I’ve never seen them do that before.

I glance at Dev. He doesn’t appear to have noticed the change in the grid. He points up.Race you.

He kicks for the surface, leaving me in a cloud of sand.

I want to stay under longer. I’m curious to see if the lights go out again, or if Socrates comes back. But my lungs are burning. Reluctantly, I follow Dev.

After I join him on the surface and catch my breath, I ask if he saw the grid flicker off.

He squints at me. ‘Are you sure you weren’t just blacking out?’

I splash his face. ‘I’m serious. We should tell somebody.’

Dev wipes the water from his eyes. He still looks sceptical.

To be honest, I’ve never understood why we have a state-of-the-art electronic underwater barrier across the mouth of the bay. I know it’s supposed to keep the sea life safe by keeping out everything else, like poachers, recreational divers and pranksters from our rival high school, Land Institute. But it seems like overkill, even for a school that produces the world’s best marine scientists and naval cadets. I don’t know exactly how the grid works. Idoknow it isn’t supposed to flicker, though.

Dev must see that I’m genuinely worried. ‘Fine,’ he says. ‘I’ll report it.’

‘Also, Socrates was acting weird.’

‘A dolphin acting weird. Okay, I’ll report that, too.’

‘I could do it, but, like you always say, I’m just a lowly freshman. You’re the big, powerful house captain of the Sharks, so –’

He splashes me back. ‘If you’re done being paranoid, I reallydohave something for you.’ He pulls a glittering chain from the pouch of his dive belt. ‘Happy early birthday, Ana.’

He hands me the necklace: a single black pearl set in gold. It takes me a second to understand what he’s given me. My chest tightens.

‘Mom’s?’ I can barely say the word.

The pearl was the centrepiece of Mom’s mangalsutra, her wedding necklace. It’s also the only thing we have left of her.

Dev smiles, though his eyes get that familiar melancholy drift. ‘I got the pearl reset. You’ll be fifteen next week. She’d want you to wear it.’

This is the sweetest thing he’s ever done for me. I’m going to start weeping. ‘But … why not wait until next week?’

‘You’re leaving for your freshman trials today. I wanted you to have the pearl for luck – just in case, you know, you fail spectacularly or something.’

He really knows how to ruin a moment.

‘Oh, shut up,’ I say.

He laughs. ‘I’m kidding, of course. You’re going to do great. You always do great, Ana. Just be careful, okay?’