UN TZU, A VERY SMART MAN, IN SPITE OF THE FACT THAT he has been dead for so long, wrote a book called The Art of War, and one of the many clever observations he made in the book was that every time something awful happens, there’s a way to turn it to your advantage, if you just look at things properly. This is not New Age California Pollyanna thinking, insisting that if life gives you lemons you can always make Key Lime pie. It is, rather, very practical advice that comes in handy a lot more than you might think.

At the moment, for instance, my problem was how to continue training Cody and Astor in the Harry Way now that they had been busted by their mother. And in looking for a solution I remembered good old Sun Tzu and tried to imagine what he might have done. Of course, he had been a general, so he probably would have attacked the left flank with cavalry or something, but surely the principles were the same.

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.

“It’s his shoe,” I said. “You can see right after.” She apparently accepted the justice of that, as she stepped back and let Cody climb onto the stool. I looked into the eyepiece to focus it, and saw that the slide was everything I could hope for. “Aha,” I said, and stepped back. “Tell me what you see, young Jedi.”

Cody frowned into the microscope for several minutes, until Astor’s jiggling dance of impatience became so distracting that we both looked at her. “That’s long enough,” she said. “It’s my turn.”

“In a minute,” I said, and I turned back to Cody. “Tell me what you saw.”

He shook his head. “Junk,” he said.

“Okay,” I said. “Now I’ll tell you.” I looked into the eyepiece again and said, “First off, animal hair, probably feline.”

“That means cat,” Astor said.

“Then there’s some soil with a high nitrogen content—probably potting soil, like you’d use for houseplants.” I spoke to him without looking up. “Where did you take the cat? The garage? Where your mom works on her plants?”

“Yes,” he said.

“Uh-huh. I thought so.” I looked back into the microscope. “Oh—look there. That’s a synthetic fiber, from somebody’s carpet. It’s blue.” I looked at Cody and raised an eyebrow. “What color is the carpet in your room, Cody?”

His eyes were wide-open round as he said, “Blue.”

“Yup. If I wanted to get fancy I’d compare this to a piece I took from your room. Then you would be cooked. I could prove that it was you with the cat.” I looked back into the eyepiece again. “My goodness, somebody had pizza recently—oh, and there’s a small chunk of popcorn, too. Remember the movie last week?”

“Dexter, I wanna see,” Astor whined. “It’s my turn.”

“All right,” I said, and I set her on a stool next to Cody’s so she could peer into the microscope.

“I don’t see popcorn,” she said immediately.

“That round, brownish thing up in the corner,” I said. She was quiet for a minute, and then looked up at me.

“You can’t really tell all that,” she said. “Not just looking in the microscope.”

I am happy to admit that I was showing off, but after all, that’s what this whole episode was about, so I was prepared. I grabbed a three-ring notebook I had prepared and laid it open on the counter. “I can, too,” I said. “And a whole lot more. Look.” I turned to a page that had photos of several different animal hairs, carefully selected to show the greatest variety. “Here’s the cat hair,” I said. “Completely different from goat, see?” I flipped the page. “And carpet fibers. Nothing like these from a shirt and this one from a washcloth.”

The two of them crowded together and stared at the book, flipping through the ten or so pages I had put together to show them that, yes indeed, I really can tell all that. It was carefully arranged to make forensics look just a tiny bit more all-seeing and all-powerful than the Wizard of Oz, of course. And to be fair, we really can do most of what I showed them. It never actually seems to do much good in catching any bad guys, but why should I tell them that and spoil a magical afternoon?

“Look back in the microscope,” I told them after a few minutes. “See what else you can find.” They did so, very eagerly, and seemed quite happy at it for a while.

When they finally looked up at me I gave them a cheerful smile and said, “All this from a clean shoe.” I closed the book and watched the two of them think about this. “And that’s just using the microscope,” I said, nodding around the room at the many gleaming machines. “Think what we can figure out if we use all the fancy stuff.”

“Yeah, but we could go barefoot,” Astor said.

I nodded as if what she had said made sense. “Yes, you could,” I said. “And then I could do something like this—give me your hand.”

Astor eyed me for a few seconds as if she was afraid I would cut her arm off, but then she held it out slowly. I held it and, using a fingernail clipper from my pocket, I scraped under her fingernails. “Wait until you see what you have here,” I said.

“But I washed my hands,” Astor said.

“Doesn’t matter,” I told her. I put the small specks of stuff onto another glass slide and fixed it to the microscope. “Now then,” I said.

CLUMP.

It really is a bit melodramatic to say that we all froze, but there it is—we did. They both looked up at me and I looked back at them and we all forgot to breathe.

CLUMP.

The sound was getting closer and it was very hard to remember that we were in police headquarters and perfectly safe.

“Dexter,” Astor said in a slightly quavery voice.

“We are in police headquarters,” I said. “We’re perfectly safe.”

CLUMP.

It stopped, very close. The hair went up on the back of my neck and I turned toward the door as it swung slowly open.

Sergeant Doakes. He stood there in the doorway, glaring, which seemed to have become his permanent expression. “You,” he said, and the sound was nearly as unsettling as his appearance as it rolled out of his tongue-less mouth.

“Why yes, it is me,” I said. “Good of you to remember.”

He clumped one more step into the room and Astor scrambled off her stool and scurried to the windows, as far away from the door as she could get. Doakes paused and looked at her. Then his eyes swung back to Cody, who slid off his stool and stood there unblinking, facing Doakes.

Doakes stared at Cody, Cody stared back, and Doakes made what I can only call a Darth Vader intake of breath. Then he swung his head back to me and clumped one rapid step closer, nearly losing his balance. “You,” he said again, hissing it this time. “Kigs!”

“Kigs?” I said, and I really was puzzled and not trying to provoke him. I mean, if he insisted on stomping around and frightening children, the least he could do is carry a notepad and pencil to communicate with.

Apparently that thoughtful gesture was beyond him, though. Instead he gave another Darth Vader breath and slowly pointed his steel claw at Cody. “Kigs,” he said agian, his lips drawn back in a snarl.

“He means me,” Cody said. I turned to him, surprised to hear him speak with Doakes right there, like a nightmare come to life. But of course, Cody didn’t have nightmares. He simply looked at Doakes.

“What about you, Cody?” I said.

“He saw my shadow,” Cody said.

Sergeant Doakes took another wobbly step toward me. His right claw snapped, as if it had decided on its own to attack me. “You. Goo. Gik.”

It was becoming apparent that he had something on his mind, but it was even clearer that he ought to stick with the silent glaring, since it was nearly impossible to understand the gooey syllables that came from his damaged mouth.

“Wuk. You. Goo,” he hissed, and it was such a clear condemnation of all that was Dexter, I at last understood that he was accusing me of something.

“What do you mean?” I said. “I didn’t do anything.”

“Goy,” he said, pointing again at Cody.

“Why, yes,” I said. “Methodist, actually.” I admit that I deliberately misunderstood him: he was saying “boy” and it came out “goy” because he had no tongue, but really, one can only take so much. It should have been painfully clear to Doakes that his attempts at vocal communication were having very limited success, and yet he insisted on trying. Didn’t the man have any sense of decorum at all?

Happily for all of us, we were interrupted by a clatter in the hallway and Deborah rushed into the room. “Dexter,” she said. She paused as she took in the wild tableau of Doakes with claw upraised against me, Astor cringing against the window, and Cody lifting a scalpel off the bench to use against Doakes. “What the hell,” Deborah said. “Doakes?”

He very slowly let his arm drop, but he did not take his eyes off me.

“I’ve been looking for you, Dexter. Where were you?”

I was grateful enough for her timely entry that I did not point out how foolish her question was. “Why, I was right here, educating the children,” I said. “Where were you?”

“On my way to the Dinner Key,” she said. “They found Kurt Wagner’s body.”