“Aww, but, Dad,” Halimah jokes, “can’t we just take a short spin around the lake?”

“I want to see what she can do in the open sea!” Dru counters.

The others clap and whoop in approval.

“Hold on,” I whisper to Ester. “How does the sub get from here to the open sea?”

“Luca was just saying there’s an underwater tunnel that leads out past the atoll.” She madly jots down this information on her note cards. “It’s probably an old lava vent. Do you think I should write lava vent or just tunnel?”

Ophelia claps twice, loud and sharp, to get our attention. “Freshmen!”

The group falls silent. For the first time, I appreciate that Ophelia is an HP teacher as well as a scientist. I bet her classes would’ve been hard. Super interesting, but hard.

“So, then,” she continues. “We will take this assignment seriously. The Nautilus has not been operated in almost two hundred years. We must give Ana, and the rest of us, time to acclimatize. It will be a bit like learning to ride a horse.”

Meadow Newman frowns. “The sub is still a machine, right? You make it sound like a wild animal!”

The Nautilus is not amused. The whole ship begins to hum.

Ester yells, “Look out!”

She hits the deck as water blasts from either side of the Nautilus’s prow, arcing backward over the top of the ship. The starboard deluge falls harmlessly into the lake, but the port-side spray soaks all of us from head to foot.

There’s a moment of stunned silence.

Meadow looks flabbergasted. “I’m sorry, Nautilus! You are a magnificent creature!”

The crew starts laughing. Top barks and shakes himself off. I can’t help but crack a smile. Now we know that the submarine has pride, good hearing, and maybe even a sense of humor, given the fact that it didn’t try to kill us.

I’m starting to think my fears were overblown. We’re among friends. We’re safe. The Nautilus just wants some respect. All we have to do is try one quick dive. Then we can fix whatever leaks occur, come back tomorrow, and try again. We have plenty of time.

That’s when Socrates breaches in the middle of the lake. He splashes down sideways, making as much noise as possible. A moment later, his head pops up at the base of the pier. He chatters, clicks, and whistles at me urgently.

“Whoa,” Gem says. “How did he find us?”

But that’s not the right question. The question is why.

“Something’s wrong,” Ester says, her water-blotted note cards forgotten in her hands.

Socrates bucks his head backward—a signal I remember well. Let’s go! Hurry!

My insides feel like they’re plunging into the Mariana Trench. My foreboding starts to make terrible sense.

“Everybody!” I yell. “Hey!”

I don’t have Ophelia’s skill at getting the class’s attention, but the alarm in my voice makes an impression. The others turn toward me.

Nelinha frowns at the dolphin, then at me.