On the way back, I thought about the conversation Earl and I had had on the way to the Valley Forest Estates sales office. How he’d wanted to confirm that Carpington had been caught on film with Stefanie, how he’d even suggested that the councilman had a pretty strong motive to kill her.

How, when we pulled into the parking lot, Earl asked whose car was whose.

And how, once we’d gotten the jump on Greenway and Carpington, Earl insisted that I stay and keep them covered while he left with their keys and moved their cars behind the office.

That would have been when he took the shovel from his pickup and put it in the trunk of Carpington’s car.

The only thing I hadn’t worked out a theory for was why Earl killed Stefanie Knight. But I had enough.

I started running, the grocery bag flopping at my side. I jogged all the way up Chancery Park, was struggling to catch my breath as I inserted my key into the door. I dumped the groceries on the kitchen counter and grabbed the phone.

I got the main police switchboard, then keyed in Lorenzo Penner’s extension. It rang three times before the voicemail cut in.

“This is Detective Lorenzo Penner. Leave a message at the tone.”

“Hi, it’s Zack Walker. Call me back as soon as you get this message.” And I left my number.

I glanced at the clock. After five. Sarah would be home soon. Where were Paul and Angie?

I’d grabbed the receiver off the phone so quickly when I’d come in that I’d failed to see the flashing message light. There were two, one from Paul and one from Angie.

Paul said, “I’m at Hakim’s, hanging out, should be home by six.”

Angie said, “I’m working in the school darkroom. I’m getting a lift, see you around five-thirty.”

Ever since that night, we’d all been very good about letting each other know where we were going to be, and if we were going to be late.

I unpacked the groceries, tore the wrapper off the ground beef and began forming patties. It looked as though Paul and Angie were going to join us for dinner, although with teenagers, you never knew until the last second who was actually hungry or not.

So I made half a dozen. Paul, if he had any appetite at all, could be counted on to eat at least two. I rinsed lettuce leaves, cut up some tomatoes, glancing every few seconds at the phone, willing Penner to call.

“Come on,” I said out loud. “I’m solving your goddamn case for you, asshole.”