“Harry,” Murphy said quietly. “Is it human?”

“Most likely,” I said. “Mortal blood is the strongest ink you can use for symbols like this in high-energy spells. I don’t think anything else could have contained the amounts of energy it would have taken to blow up this building.”

“It’s a pentacle, right?” Murphy asked. “Like the one you wear.”

I shook my head. “Different.”

“How so?” Her mouth twitched at one corner. “Other than the blood, I mean.”

“A pentacle is a symbol of order,” I said quietly. “Five points, five sides. It represents the forces of air, earth, water, fire, and spirit. It’s contained within a circle, the points touching the outer ring. It represents the forces of magic bound within human control. Power balanced with restraint.” I gestured at the symbol. “See here? The points of the star fall far outside the ring.”

She frowned. “What does it mean?”

“I have no idea,” I said.

“Gosh,” she said. “You’re worth the money.”

“Ha-ha. Look, even if I’d seen this symbol before, it could mean different things to different people. The Hindus and the Nazis have very different ideas about the swastika, for example.”

“Can you make a guess?”

I shrugged. “Off the top of my head? This looks uncomfortably like a combination of the pentacle and the anarchy symbol. Magic unrestrained.”

“Anarchist wizards?” Murphy asked.

“It’s just a guess,” I said. My gut told me it was a good one, though, and I got the impression that Murphy had the same feeling.

“What’s the symbol for?” Murphy asked. “What is it meant to do?”

“Reflect power,” I said. “My guess is that the energy that drove through the building was reflected from this sigil, which means…” I kayaked down a logic cascade as I spoke. “Which means that the energy had to come in from somewhere else first.” I turned around slowly, trying to judge the angles. “The incoming beam must have gone right through the collapsed part of the building and-”