“Real magic shifts and changes shades,” Julie said. “Ghoul magic looks yellow-orange but it’s more like streaks of olive and orange mixing together with some really light brown. Even the vampires have traces of red and blue in their purple.” She glanced up. “Whatever that is, it’s very uniform. There are very light flecks of gold and silver in it, but most of it is one color.”

A uniform magic signature meant whatever made it emitted very concentrated specific magic. “Any blue?”

Julie shook her head.

Blue stood for human magic. Any sort of human derivative, like a ghoul’s or a shapeshifter’s, showed blue in their magic signature. They could never completely get rid of the traces of their humanity. Whatever this was didn’t start out as a human.

I rubbed my face. It didn’t give me any new insights. “Whereabout is this copper?”

Julie frowned. “About four feet above the car.”

I stepped onto the Tahoe’s hood and climbed onto its roof.

“What are you doing?” Curran asked.

“I don’t know. I’m just trying to get a sense of things.” I stood up.

“Okay, you’re in it,” Julie said.

I didn’t feel anything. I stared up at the sky, waiting for a clue to fall out of the heavens and land on my head. At this point, I’d welcome the hit.

From here I could see the whole cave, the two tunnels, the whole area from which we had come, the dirt floor against which the Tahoe had impacted, the loose soil churned by the ghouls as they scrambled across it. A glint caught my eye to the right. Something shiny reflected the light among the dirt. An identical spark glowed to the left, exactly the same distance. Hmm. I turned slowly. More sparks, buried under the dirt.

I slid off the Tahoe. From here the glint was invisible. I pulled some gauze out of my pocket, knelt in the spot I thought I saw it, and brushed at the dirt. The loose soil slid aside, revealing a narrow ribbon of translucent shiny sand. It looked brittle, but held together as if some great heat had touched the sand and half fused it into glass.

Julie knelt next to me and reached to brush more dirt off.

“Don’t touch it.” I passed her the gauze. The first rule of staying alive in Atlanta: if you see something weird, stay the hell away from it.

We began brushing the dirt aside, Julie and I from one side, Curran and Derek from the other. In twenty minutes we had it cleared and I climbed the Tahoe again. A perfectly round ribbon of glass sand, about eight inches wide, circled the vehicle, lying on top of the dirt like a thin crust of dirty ice on the surface of a pond after the first frost. Someone, probably the ghouls, had tried to cover it, but there it was.