“Oh.” Perhaps I’d been too optimistic about this arrangement. Or her level of intelligence. “See, if I tell you that, then I lose my leverage, and—”

“I understand how this arrangement works,” Tamara said, with very forced politeness. “But if I’m going to guide you to the Philosopher Stone, I need to know that I’m leading you to the right general area. I’m guessing that the Philosopher Stone is in one of the odd-numbered labs.”

Lab 17, in fact. “Good guess,” I said.

Tamara grimaced, whether at my answer or at the way her broken arm jostled as she shifted her weight. “We will have to go through the engine, then.”

“Explain.” Indigo set his knife aside.

“Have you still got that pathetic water bottle?” Tamara asked me.

“Do you mean the innovative creation of a man in peril, valiantly making do with limited resources? No, I lost it,” I said. “Why?”

“Then have you got your notebook and pen?”

“In a useless, waterlogged form.”

“Tell me you still have my tablet.”

“That I’ve got.” I pulled it out of my jacket pocket and passed it over to her. She took it one-handed, careful with her injured arm. “Can we, I don’t know, do something about your arm?”

“If you still had your dented tin, I was going to shape it into a cast,” Tamara said. “I’ll find some old strips of metal and splint it before we leave.”

“There’s no need.” Indigo shifted onto his knees, leaving his sword on the floor. He pulled something out of the pockets strapped to his hips—the portable medical device he’d used to save me from radiation burns, and to close up the claw wounds on his hand.

“Isn’t that just for surface wounds?” I asked.

Indigo pressed some buttons on the screen, and from the nozzle a long, thick needle slowly extended. “It does many things.”

“I’ll splint it, thanks,” Lantern-Eyes said.

“It takes six to eight weeks on a human to heal a broken bone,” Indigo said. “It will take two hours before your arm is at its prior strength, using this device. Would you like a working arm, Lieutenant Gupta?”

Tamara chewed her cracked bottom lip. Then she said, “Let me see it.”

Indigo leaned forward, the medical device extended out, needle facing him. Tamara reached out and grabbed it by the other end, avoiding his hand. She set it in her lap and examined it for a minute with an expression that suggested she was getting a lot more out of her examination of the alien device than I’d gotten out of my brief glance.

“Do you know what you’re looking at?” I asked her.

“Some of this is strange—it’s set to Minister baselines, not human?”

Indigo did not reply. Tamara cradled the device in her good hand and looked down on it like a poor man handed a palmful of gold.

Indigo said, “It will work on a human bone.”

“It’s very impressive,” Tamara said, and offered it back to Indigo. I wondered if I were imagining the reluctance in her expression. “Yes, Minister. I would like a usable arm.”