Top trots along beside us. He’s the only one who doesn’t look nervous. Ophelia leads us down a corridor that is perfectly round, like it was bored into the heart of the volcano by a single massive drill bit.

“Is Luca coming?” I ask.

“He’s already there,” Ophelia says.

I’m tempted to ask where exactly there is, but I have a feeling I’ll find out soon enough. I wonder if I should have waited for Gem to come with us. I imagine he’ll give me a hard time about that later. Somehow, though, I’m not sure a hyper-protective, heavily armed bodyguard would make me any safer this morning.

At the far end of the corridor stands a metal hatch that reminds me of an old bank-vault door.

“Was—was this here before?” I ask. “I mean, in Nemo’s time?”

Ophelia looks at me curiously. “What makes you ask?”

I have to think about this. The door’s plating and gear work don’t show any signs of wear or corrosion. The style is similar to other alt-tech devices I’ve seen, like the LOCUS and the Leyden cannon. But the vault door seems to radiate weight and power.

“It seems old,” I decide. “Like, really old.”

Ophelia gives me a dry smile. “Very astute, Ana. From this point forward, we will be entering Nemo’s original base. This door was sealed by Cyrus Harding shortly after Nemo’s death. It remained shut until we excavated it two years ago, when your father opened it.”

Ester hugs her shivering arms. “But the volcanic eruption destroyed the island. It said that in The Mysterious Island.”

“Yes, well…” Ophelia peers over the top of her glasses. “Harding and Pencroft may have stretched the truth a bit when they spoke to Jules Verne. Adventurers and treasure hunters were less likely to search for the island if they believed it had been obliterated.”

“So the book lied.” Ester sounds offended, as if her meticulous note cards have betrayed her. “That explains…”

She stops herself. In the dim overhead light of the corridor, her skin looks like stressed coral, slowly losing its healthy pink.

“What is that metal?” Nelinha asks our host. “It isn’t steel or brass. It doesn’t seem to corrode.”

“Ingenious, isn’t it?” Ophelia agrees. “For lack of a better term, we call it nemonium. We still have not managed to re-create the alloy, though we can work with it and repurpose old pieces for our own alt-tech. As far as we can tell…”

She launches into a detailed analysis of nemonium’s tensile strength, malleability, and density that I’m sure several people in the world could understand, one of them being Nelinha. Meanwhile, I turn to Ester and whisper, “You okay?”

She chews her thumb. I resist the urge to pull her hand away from her mouth.