So as I led Cody and Astor to their weeping mother I was beating the bushes in the dark forest of Dexter's brain for some small partridge of an idea that the old Chinese general might approve of. And just as the three of us trickled to a halt in front of sniffling Rita, the idea popped out, and I grabbed it.

"Rita," I said quietly, "I think I can stop this before it gets out of hand."
"You heard what-This is already out of hand," she said, and she paused for a large snuffle. "I have an idea," I said. "I want you to bring them down to me at work tomorrow, right after school." "But that isn't-I mean, didn't it all start because-"
"Did you ever see a TV show called Scared Straight?" I said.
She stared at me for a moment, snuffled again, and looked at the two kids.

And that is why, at three thirty the next afternoon, Cody and Astor were taking turns peering into a microscope in the forensics lab. "That's a hair?" Astor demanded.

"That's right," I said.
"It looks gross!"

"Most of the human body is gross, especially if you look at it under a microscope," I told her. "Look at the one next to it." There was a studious pause, broken only once when Cody yanked on her arm, and she pushed him away and said, "Stop it, Cody."

"What do you notice?" I asked.
"They don't look the same," she said.
"They're not," I said. "The first one is yours. The other one is mine."

She continued to look for a moment, then straightened up from the eyepiece. "You can tell," she said. "They're different." "It gets better," I told her. "Cody, give me your shoe."

Cody very obligingly sat on the floor and pried off his left sneaker. I took it from him and held out a hand. "Come with me," I said. I helped him to his feet and he followed me, hopping one-footed to the closest countertop. I lifted him onto a stool and held up the shoe so he could see the bottom. "Your shoe," I said. "Clean or dirty?"

He peered at it carefully. "Clean," he said.

"So you would think," I said. "Watch this." I took a small wire brush to the tread of his shoe, carefully scraping out the nearly invisible gunk from between the ridges of the tread into a petri dish. I lifted a small sample of it onto a glass slide and took it back over to the microscope. Astor immediately crowded in to look, but Cody hopped over quickly. "My turn," he said. "My shoe." She looked at me and I nodded.