It was so small I had walked almost completely through it before I felt it. It felt almost like walking into air-conditioning. The residual magic felt cold, like the other dark power I'd touched, terribly cold, and my skin erupted in goose bumps. I stopped on the spot, closed my eyes, and focused on the remaining energy.

It felt strange somehow. Dawn had dispersed most of the energy that had been there, but even as an aftertaste of the magic that had been worked there, the cold was dizzying. I'd felt dark power similar to this before today—similar, but not identical. There was something about this that was unlike the horrible aura surrounding Grevane, or that I had sensed from wielders of black magic in my past. This was undeniably the same power, but it somehow lacked the greasy, nauseating sense of corruption I'd felt before.

That was all I could sense. I frowned and looked around. There was a spot on the sidewalk that might have been a half-cleaned bloodstain, or might have been spilled coffee. Around me, business-day commuters came and went, some of them pausing to give me annoyed glares. Cars purred by on the street.

I checked at the pharmacy, but the place had been closed the night before, and no one had been there or heard about anything out of the ordinary. I checked the neighboring places of business, but it was a part of town where not much was open after six or seven in the evening, and no one had seen or heard about anything out of the ordinary.

Most of the time the investigation business is like that. You do a lot of looking and not finding. The cure for it is to do more looking. I walked back to the SUV and went to the next spot on the map, at the Field Museum.

The Field Museum is on Lake Shore Drive, and occupies the whole block north of Soldier's Field. I felt a brief flash of gratitude that things usually went to hell during the workweek. If this had been a Sunday with the Bears at home, I'd have had to park and then backpack in from Outer Mongolia. As it was, I got a spot in the smaller parking lot in the same block as the museum, which cost me only a portion of the national gross income.

I walked to the entrance from the parking lot, and slowed my steps for a few strides. There were two patrol cars and an ambulance parked outside the Field Museum's main entrance. Ah hah. This stop looked like it might be a bit more interesting than the last one.