Up through that post, Petra’s tone had been like her speaking voice, breezy, confident. A few days later, she wrote more soberly.

I thought they promoted me because I did such a great job. Turns out it was because I can’t keep my big mouth shut. I said some stuff about something that the Strangler wants to know more about, something that happened a million years ago that could come back to bite my candidate. It’s so confusing. It’s something I said, but I have no idea what, but now the Strangler says I have to dig it up, even though I don’t know anything about what happened or even what I’m really looking for.

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.

2. The house in South Chicago, where Petra had stood watching when the thugs threw their smoke bomb through the window.

3. The Nellie Fox baseball.

4. Her obsession with whether my dad had left a diary.

5. Her arrival at the Freedom Center the night I went to collect evidence.

6. Her nervous whisper that she couldn’t look for the contractors who’d been hustled into Sister Frankie’s apartment.

It was four in the morning. I’d slept for seven hours, until Rose Hebert’s phone call woke me. But fatigue, born of stress, my still-healing body, and my recent sleepless nights, was overwhelming me. I went into the little back area and reassembled my cot and air mattress. Oblivious to the threat of another break-in, I sank back into sleep.

IN MY DREAM, MISS CLAUDIA WAS STANDING OVER ME. “Lamont will come back,” she said in clear, plain speech. “My Bible tells me so.” She was waving her red leather Bible under my nose. She shook loose the dozens of cardboard page markers. When I put my hands out to catch them, they turned into photographs and floated to the floor before I could reach them.

If I could only study them, they would tell me exactly where Petra was and why she’d run away. But when I gathered up the pictures, they burst into flames in my hands. And suddenly I was holding Sister Frankie, her skin yellow-white beneath the burning candle of her hair. Behind her, Larry Alito and George Dornick were laughing with Harvey Krumas and my uncle. And Strangwell was there, pointing to my uncle and saying, “You know why she had to die.”

I woke sweating and weeping. For a moment, I was disoriented in the black space. I thought I was back in Beth Israel, with bandages over my eyes, and I flailed around my cot trying to find the call button for the nurse. Awareness gradually returned. I swung my legs over the edge of the cot and fumbled my way to a light switch, moving slowly to keep from tripping over the drawers that had been dumped on the floor.

It was eight in the morning, long past time for me to get going. My lease-mate has a shower at the back of her studio because she welds big pieces of steel and polishes them with caustic substances and needs to be able to wash off in a hurry. I stood under a cold spray of water, trying to wake myself up, and returned, shivering, to my own office to put my clothes back on.

I picked up the list I’d made in the middle of the night of the things that Petra seemed to be trying to track and took it with me to the coffee shop across the street. While I waited in line for my espresso, I saw Elton Grainger out front hawking Streetwise and accepting donations with his usual unsteady bow and flourish. I took my drink, along with a bag of fruit, yogurt, juice, and some rolls, and went out to the street.

“Elton! I’ve been hoping for a word with you.” I held out the bag. “Help yourself. Juice? Muffin?”

“Hey, Vic.” His bloodshot blue eyes shifted uneasily from me to the sidewalk. “I’m okay. Don’t need no food today.”

“You always need food, Elton. You know what the doc said at the VA when you passed out in June: you have to stop drinking and start eating so it doesn’t happen again.”

“You leave me to sort that out. I don’t need you hovering over me.”

“Okay. No hovering. You know my place was seriously busted two days ago. I wonder if you saw who went in?”

“Vic, I told you before, I ain’t your doorman.”

I pulled a twenty from my wallet. “Early Christmas tip for the non-doorman. My cousin was there. I want to know if you can ID the two people she was with. They were all wearing coats, even though it was September and hot.”

He eyed the twenty but shook his head. “Don’t know any cousin of yours, and that’s a fact.”

“My cousin, Elton-the tall, cute blonde-you met her with me a couple of times, right after you got out of the hospital. Petra.”

“Sorry, Vic. I know you saved my life and all, but I never heard of her.” He turned away from me to greet a couple who were heading into the shop. “Streetwise. New edition today. Streetwise.”

I couldn’t get him to look at me again. Finally, I pushed the twenty into his hand, along with a blueberry muffin, and walked up the street toward Armitage.

I was fuming. Someone had gotten to Elton, scared him into silence. I should have swung by my office yesterday before starting my journey to South Chicago, should have talked to Elton then. If me saving his life, let alone the twenty-the price of a bed for a night or a week in the tank-couldn’t budge him, someone was putting heavy pressure on him.

Strangwell wouldn’t shake down a homeless guy personally, that was way beneath him. But he knew people who would. Larry Alito, for one. I’d seen him with Les Strangwell the day before Petra disappeared. Strangwell gave him an assignment: “I know what Les wants,” he’d snapped at someone who called to check up on him. Could it have been Dornick?