She led us into a rectangular tunnel, thirty feet wide and twenty high. The other two guards hauled the door shut, and I heard heavy bolts clunk into place, trapping us down here. The only way out now was by the good graces of our vampire hosts.

I gawked openly as we walked. White salt crusted the rock walls, glittering in the dim, blue-tinged light from a series of LED bulbs. Bare electrical cables ran from the lights to thick metal conduits running along the ceiling. A battered pickup truck was parked against the wall to the right of the elevator. The bottom was rusted brown, and a layer of salt painted the rest white. A pair of well-maintained dirt bikes were tucked into the corner behind the truck.

“How big is this place?” Lena asked, looking around.

“Miles,” I said. “There were two major salt mines beneath Detroit. One continues to operate today, but the vampires spent a great deal of time and money to get the second mine erased from the records, giving them a relatively safe place to live.”

“Listen to Mister Tour Guide,” chuckled Kyle.

We passed tunnels and staircases carved into the walls, along with several small maintenance trucks. “What’s over there?” I asked, pointing to a green metal door.

“Freight elevator,” said the guard. “We’ve only got two elevators large enough for vehicles.” Her ink-black brows drew together. “I probably shouldn’t have told you that.”

I pantomimed turning a key in my lips, even as I tried to orient myself and figure out where such an elevator might emerge. We hadn’t walked very far yet, but there was no guarantee the shaft was vertical. “What about that one?”

“Mausoleum,” said Kyle. “Close to a hundred coffins, each lined with the dirt from a different vampire’s native home. Beyond that is a storage unit. The humming you hear is a bank of industrial refrigeration units.”

I didn’t have to ask what they were keeping refrigerated. “You couldn’t run this place on generators. I assume you’ve got someone at Detroit Edison siphoning electricity and hiding the evidence?”

Neither vampire answered, not that I expected them to. I studied other vampires as we walked. A wizened-looking creature with gray skin and long, clawed fingers lounged against the wall, smoking a clove cigarette. Two inhumanly gorgeous women sat hunched over a chessboard. A boy who looked no older than thirteen clung to the wall like Spider-Man, working on an electrical junction box of some sort.

I stepped toward a tunnel which was curtained off with thick plastic sheeting. Neither of my undead escorts stopped me, so I shoved the curtain to one side, revealing artificial sunlight and a cave of green. “You’re farming?”

“Hard to do with all the salt,” said the guard, “but yes.”