“My mom told me once that I was shaping up to be an idealist,” Dani said. “I think she’s probably right. I had a report I was supposed to do in history, at the end of sixth grade back in L.A. The teacher gave us a list of topics to pick from, and I picked the Tuskegee Airmen. Have you heard of them?”

“Red tails,” Sam said. He’d gotten into model airplane building over the past couple years—part of a growing obsession he seemed to have with all things military. He’d started out with modern warplanes like the F-14 and the B-1, but soon fell in love with World War II aircraft. You couldn’t get very far into that subject without learning about the Tuskegee Airmen, the all-black fighter squadron that had turned out to be just about the best bomber escort group in the whole war. Sam’s favorite model, packed carefully in a box in his bedroom right now, was the P-51 Mustang flown by Lee Archer: Ina the Macon Belle.

“When I went to the library to do my research on them,” Dani said, “I found something else Tuskegee is known for. It probably wasn’t something my sixth-grade teacher wanted a report on. Have you heard of the Tuskegee syphilis experiment?”

“Gotta go with no on that one.”

“You know what syphilis is, though.”

“Yeah,” Sam said. As awkward as sex ed had been, the material was pretty much impossible to forget.

“Well, in Tuskegee,” Dani said, “the United States government ran an experiment to measure what that disease could do to people if it went untreated for a really long time. You know how they did that? They brought in hundreds of men who had the disease, and told them they were going to treat them for it. And then they didn’t. They didn’t even tell them they had syphilis. They gave them some b.s. diagnosis so they wouldn’t know enough to go get treatment somewhere else. They kept them clueless for forty years, suffering from the disease, probably passing it to their wives or their girlfriends. Forty years, and at any point along the way they could have given them ten days’ worth of penicillin and cured them. There ended up being six hundred victims of that experiment, and every last one of them was black. Think about that. This really happened. And recently. It only ended in 1972, after somebody told a reporter about it. That’s only five years before we were born. That’s what I mean by other kinds of secrets.”

There was a little tremor in her voice, just detectable. In the indirect flashlight glow bouncing up off the concrete, Sam could see a sheen in her eyes. She blinked and turned away, sweeping her beam quickly over the smashed ruins of vehicles in the chamber.