It’s like Spy vs. Spy, and I have to spy on my DC, which in some ways is fun, seeing if I can outsmart a person who’s been a detective for twenty years. But mostly I hate it, because the Strangler says I can’t trust anyone. He says if I tell a single soul what I’m looking for, it could get people killed, especially if I tell my detecting cousin. The Strangler says she’ll go out of her way to hurt people I care about, and I know that when she’s angry she goes off the deep end. She saved this homeless guy’s life, but she almost killed me because I didn’t respect her mother’s dress. So watch Campaign Girl morph into Undercover Girl.

A week went by, and Petra made her final post.

If you say something that puts everyone you care about in danger only you don’t know that it’s a big secret, are you really to blame? And then how do you know who is your friend and who is your enemy? I can’t tell anymore. I wish I’d never come to Chicago, but it’s too late. I can’t go home.

I sat back in my chair and rubbed my eyes. Petra, with her perpetual cheerful broadcasting of everything she knew, had said something that put the powerful people around her on alert. DEFCON 3 and dropping. I could hear the alarms ringing in Les Strangwell’s office.

I didn’t know the things that Petra might have talked over in the office—these clearly ranged from my breaking into her apartment for her, since one of her Web posts dealt with that, to my visiting Johnny Merton—because she’d even blurted that out at the Navy Pier fundraiser. Certainly, anyone reading the posts on her MySpace profile would know what she was doing. I imagined the Strangler coldly reading over her shoulder. He could be any one of those five hundred “friends,” invisible, like a shark floating under her toes.

I had an uncomfortable memory of the morning in my apartment when I’d blown up over her pawing through my trunk. My anger had frightened her, and it had created a gulf between us. I thought again of all the times my dad had told me my temper would get me into serious trouble. My God, he’d been right, but I’d never taken his words seriously to heart.

I had to find Petra. I didn’t even know where to begin my search. I felt like something large and clumsy, a rhinoceros, easy to spot as it crashed through the underbrush and about as effectual an ally in times of trouble.

I made a list of things I’d said or done and things Petra seemed interested in:

1. Johnny Merton and the Anacondas.