“So we’re talking mojo,” Murphy said.

“Well, technically mojo isn’t-”

She sighed. “Are we dealing with magic or not?”

As if the scent of Hellfire weren’t enough to give it away. “Yeah.”

Murphy nodded. “You call up fire all the time,” she said. “I’ve seen it do a lot of things that didn’t look like normal fire.”

“Oh, sure,” I said, holding my hand over the surface of the flame-bored bricks. They were still warm. “But if you want to control it once you call it up, it takes additional energy to focus the fire into a desired course. Controlling the energy is usually as much effort as the fire itself, if not more.”

“Could you do something like this?” she asked, gesturing at the building.

Once upon a time she would have inflected that question a whole lot differently, and I’d have gotten nervous about whether the hands in her pockets were holding a gun and handcuffs. But that had been a long time ago. Of course, back then I probably wouldn’t have given her a straight answer either, like I would now.

“Not a chance in hell,” I said quietly, and not entirely metaphorically. “I’m pretty sure I couldn’t call up this much energy in the first place. And even if I could, I wouldn’t have anything left to control it with.” I closed my eyes for a moment, trying to feel any lingering traces of power around the area, but the destruction and subsequent drift of dust and snow and smoke had obscured any coherent patterns that might have given me hints about how the working had been accomplished.

I did, however, notice something else. The surface of the cut was not perpendicular to the wall of the building. It went in at an angle. I frowned and squinted back behind me, trying to line it up with the wall of the building on the other side of the alley.

Murphy knew me well enough to see I’d noticed something, and I knew her well enough to see her sudden interest make furrows between her eyebrows as she forced herself to be quiet and let me work.

I got up and went to the far side of the alley. A light coating of snow and dust had coated the wall.

“Watch your eyes,” I murmured, squinting my own to slits. Then I raised my right hand, called up my will, and murmured, “Ventas reductas .”

The wind I called up wasn’t the usual burst I commonly used. It was far more toned-down than that, and it poured steadily from my outstretched hand. All the work I was doing with Molly had allowed me to rethink a lot of my basic evocations, the fast and dirty magic that wizards used in desperate and violent situations. I’d been trying to teach the spell to Molly, but she didn’t have the raw strength I had, and it would have practically knocked her unconscious to call up a heavy blast of air. I’d modified my teaching, just to get her comfortable with using a bit of air magic, and we’d accidentally developed a passable impersonation of an electric blow-dryer.

I used the dryer spell to gently brush away dust and snow from the wall. It took me about a minute and a half, and when I was finished I caught another scent under the brimstone stench and said, “Double crap.”

Murphy stepped forward with her flashlight and shone it on the wall.

The sigil had been painted on the wall in something thick and brown that smelled like blood. At first I thought it was a pentacle, but I saw the differences immediately.

“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-”

“Beam?”

I pointed at the semicircular hole in the ruined wall. “Yeah. Heat energy, a whole lot of it.”

She studied the hole. “It doesn’t look like it would be big enough to take down the building.”

“It isn’t,” I said. “Not in an explosion, anyway. This just drilled a hole. Might have started a fire as it went, but it couldn’t have sheared off the front of the building like that.”

Murphy frowned, tilting her head. “Then what did?”

“Working on it,” I mumbled. I judged the angles as best I could and took off down the alley. The firemen were still hard at work on the building, and we had to walk over several hoses as we emerged into the street at the back of the apartment building. I crossed the street and walked down the length of the building there, my hand raised, senses questing for any residual magic. I didn’t find any, but I did smell Hellfire again, and a couple of feet later I found another not-pentacle, identical to the first, also hidden under a light dusting of snow.

I kept going clockwise around the ruined building. I found two more symbols on the undamaged building on its next side, and one more across the street from the front of the ruined apartments, and then I completed the circle, arriving back at our original reflective symbol.

Five reflection points, which had guided a truly freaking frightening amount of energy through the building, forming one single, enormous shape as they did.

“It’s a pentagram,” I said quietly.

Murphy frowned. “What?”

I touched the round, smooth bore mark on the destroyed building’s wall. “The beam of energy that ripped through the building right here was one of five sides of a pentagram. A five-pointed star.”

Murphy regarded me blankly.

I reached into my pocket and pulled out a piece of chalk. “Okay, look. Everyone learns to draw this in grade school, right?” I quickly sketched out a star on a clear bit of brick wall-five strokes of the chalk, forming five points. “Right?”

“Right,” Murphy said. “You get them from the teacher when you get an A.”

“Another example of symbols having disparate meanings,” I said. “But look here, in the middle.” I filled in the closed shape in the center of the star. “That’s a pentagon shape, see? The center of the pentagram. That’s where you contain whatever it is you’re trying to contain.”

“What do you mean, contain?”

“A pentagram like this one is a symbol of power,” I said. “It’s got a lot of uses, depending on how you employ it. But most often you use it to isolate or contain an entity.”

“You mean like summoning a demon,” Murphy said.

“Sure,” I said. “But you can use it to trap other things too, if you do it right. Remember the circle of power at Harley MacFinn’s place? Five candles formed the pentagram on that one.”

Murphy shuddered. “I remember. But it wasn’t this big.”

“No,” I admitted. “And the bigger you make it, the more juice it takes to keep it going. I’ve never, ever heard of one that would take this much energy to activate.”

I drew little X shapes at the points of the star and drew the chalk from one to the next, thickening the lines of the example pentagram. “Get it? The beam streamed from one reflector to the next, melting holes through the building as it went. The reflectors formed the beam into one huge pentagram at ground level, more or less.”

Murphy frowned and squinted at the simple diagram. “The center of that shape couldn’t have covered the whole building.”

“No,” I said. “I’d need a good map to be sure, but I think the center of the pentagram must have been about twenty feet back from the front door. Which is why only the front half of the building collapsed.”

“The explosion came from inside this pentagon thing? Magical TNT?”

I shrugged. “The explosion came from inside the pentagram’s center, but not necessarily from the pentagram. I mean, it could have been a normal device of some kind.”

“Square in the middle of the giant, scary pentagram?” Murphy asked.

“Maybe,” I said, nodding. “It depends on what the pentagram was being employed for. And to know that, I’d have to know which way was its north.” I circled the topmost point of the chalk pentacle. “The direction of the first line, I mean.”

“Does it make a difference?”

“Yeah,” I said. “Most everybody draws those stars just like I did. Bottom left to the topmost point as the first stroke. That’s how you draw it when you want to defend something, ward something away from a location, or banish a spiritual entity.”

“So this could have been a banishing spell?” Murphy asked.

“It’s possible. But you can do a lot of other things with it, if you draw it differently.”

“Like build a cage for things,” Murphy said.

“Yeah.” I frowned, troubled. “Or open a doorway for something.”

“Which, judging by your face, would be bad.”

“I…” I shook my head. I didn’t even want to know what kind of terror would need a pentagram that huge in order to squeeze into our world. “I think if something sized to fit this pentagram had come through it, there would probably be more than one building on fire.”