‘Ester.’ I push the box gently back to her. ‘I trust you. We’ll figure out the details later, but I can’t imagine a world without Harding-Pencroft Academy. As Prince Dakkar’s descendant and captain of theNautilus, I ask you to please take this gift. I know you’ll make HP even better than it was.Wewill, together.’

Her mouth quivers. She blinks back tears. For a moment, I worry I may have misjudged her wishes and given her a burden she didn’t really want.

Then she says, ‘I love you. I’m going to put this under my bunk.’

And off she goes with Top at her heels.

As I stand alone in the treasury, I wonder if Nemo ever worried about his crew walking off with a few hundred million in gold and jewels. I guess not. What would it have mattered to him if they did? The sea gave him everything he needed.

Yet with all his wealth and advanced tech, he still ended his life bitter and defeated. He was so alone he had to trust his legacy to shipwrecked strangers.

He didn’t believe in humanity. He didn’t believe in himself. He tried and failed to change the world – and ended up being written off as a fictional character.

I think about Dev aboard theAronnax. I remember him telling me hehadto destroy HP because it was the only way to take what was rightfully ours: this ship, Nemo’s legacy.

I wish he were here now. I would punch him. Then I would give him a hug. Next I would force him to look at all this wealthand see how pointless it was for Nemo. Absolute power can corrupt anyone. Nemo knew that. In the end, all he could do was bury himself with his sub and his riches and hope that maybe some day human nature would improve to the point where we could handle his power.

And yet here we are, more than a century and a half later, still fighting over theNautiluslike it’s a prized toy in the sandbox.

Someone grunts behind me, breaking me out of my thoughts.

I turn to find Jupiter waiting for my attention. He looks past me at the room full of treasure. Then he signs,Where did your crew put my muffin pans?

I have to smile. At least orangutans have their priorities straight.

‘Let’s go look,’ I tell him.

We head off in search of real treasure. We can’t use billions in the middle of the Palau Trench, but we can definitely use Jupiter’s blueberry muffins.

Day and night don’t mean much underwater, but I spend the hours until dinnertime checking on my crew around the ship, helping out where I can.

TheNautilusis acting cranky. I suppose she didn’t like being called an antique piece of junk by the crew of a newer submarine, then running from a fight by shooting halfway across the Pacific. I soothe her with compliments and promises that we will get her back in fighting shape, if she’ll just let us work without shocking us or spewing gunk in our faces.

I guess she understands at least some of my submarine-whispering. By day’s end, the Cephalopods have restored basic propulsion. The cav-drive will take longer, but that’s fine by me. I’m not anxious for another test run until we’ve figured out the seat-belt situation.

When we reconvene for our evening meal, everyone seems in a better mood. At this point, each day we stay alive is a win, but we’re also making progress on repairs. Jupiter’s food continues to make our bellies happy. And word has got around about Nemo’s treasury.

I left the vault door open so all the crew members could take a look. I made it clear that if anyone wanted to walk away afterwe’ve finished repairs, they could do so and become an instant billionaire.

So far, there haven’t been any takers. Everyone seems determined to get theNautilusin order, return to Lincoln Base, save our friends and defeat theAronnax. Afterwards (if thereisan afterwards) we can figure out how to rebuild HP with our newfound shiny pretties. This doesn’t stop the crew from calling one another billionaires, however. Nelinha is now Billionaire Engineer da Silva, I am Billionaire Captain Dakkar, and Jupiter is the Billionaire Gourmet Orangutan.

I think Nemo might have been wrong about human nature. There are good people in the world. Despite what happened with Dev and Land Institute, despite Harding-Pencroft’s own failures, this crew is made up of people I trust.

I go to sleep that night in my ancestor’s stateroom, staring at the conch-patterned bas-relief on the ceiling. I wonder what theNautilusthinks of her new crew. I hope, as we continue to clean her ancient brain, she doesn’t start remembering the downsides of working with humans.

The next day is my fifteenth birthday. Ester and Nelinha bring me a cupcake for breakfast and sing to me quietly, but they understand I don’t want any other recognition. We have so much else going on, and so little to celebrate … Also, I donotwant to spend this day reflecting on how much has changed in the past year, or even the past week. And, as for blowing out candles and making wishes, I’m not sure I could express any of my wishes without breaking into tears. Better to just keep moving forward.

We’ve given ourselves a week to repair the ship, which isn’t nearly enough time, but we also know that every day we spend here is another day our friends are prisoners of Land Institute.

I wish I could believe theAronnaxhad left Lincoln Base alone. I’d feel relieved if I knew they were following theNautilus,hoping to catch us. But I suspect Lee-Ann was right about Dev taking hostages and waiting to see if we would come back. I just have to hope this old submarine still has some surprises up her torpedo tubes. We have to figure out a way not to cav-drive ourselves right into a trap. Otherwise, all our tech and all that treasure in the hold aren’t going to do us any good.

The day after my birthday, we finish de-gunking the innards of theNautilus.As near as Nelinha can tell, the cav-drive is back online. The Sharks repair the forward and aft Leyden cannons. They also manage to piece together two working torpedoes by cannibalizing parts from the others on board.

‘They would have exploded in the bay if we’d tried to fire them at theAronnax,’ Gem assures me. ‘So it’s a good thing we didn’t.’

The next day, Halimah and Jack get the skiff operational and take it out for a spin. They manage not to crash or drown. Robbie figures out how to run Jupiter’sGreat British Bake OffBlu-rays through the LOCUS display in the galley, so our chef can watch Mary Berry in holographic purple 3-D (which is just as terrifying as it sounds). I discover that Captain Nemo’s keytar can be synched with the bridge’s pipe organ, so I can play music from anywhere in the ship.

‘Or even outside the ship,’ Ester guesses. ‘That keytar thing looks waterproof. I bet you could broadcast music while you’re in the deep.’