Doyle’s excavation was a work of thoughtful engineering.

The length of the subterranean construction wasn’t exactly mind-boggling; the distance between the south side of Doyle’s basement and the north side of the Miller home was only about fifteen feet. And this wasn’t a highway tunnel; the diameter of the mostly round bore ranged from a maximum of about thirty inches a few feet from where it began behind the Spielberg movie screen to as narrow as twenty-four inches or so near the Millers’ house. Parallel tracks of angle iron were embedded in the flat floor of the tunnel all the way from one end to the other. A long string of outdoor holiday lights-white only-were stretched along the entire distance to provide illumination.

The slope of the tunnel-it ran downhill at a steeper angle than I would have expected-was curious to me, but my initial impression was that the slope was deliberate. It appeared that the floor of the tunnel dropped about six or seven feet over its short length. A husky winch was bolted to the outside of Doyle’s foundation wall and a sturdy stretch of conduit connected it to the house’s electrical system. The stout cable from the winch was hooked to one end of an ingenious contraption that was constructed of four sets of skateboard wheels topped with two narrow, interconnected sections of thick plywood, loosely hinged in the middle. The wheels of the makeshift sled fit perfectly into the angle iron tracks that had been set in the tunnel floor.

A flimsy remote-control unit jerry-rigged from a garage-door opener would have allowed Doyle to operate the winch from any location in the tunnel. By climbing prone onto the sled, hanging on, and pressing the remote-control button, Doyle could either slowly extend or retract the cable on the winch, which would either lower the sled farther into the tunnel toward the Millers’ house or pull it back up the slope toward his own house.

Simple. Elegant.

Building the tunnel would have been tedious, no doubt. But if Doyle had managed only six inches of fresh digging a day, he could have completed the excavation in a little over a month. A foot a day and he’d have been done in a fortnight. The dirt that he’d removed from the tunnel was undoubtedly part of the weaving contours and berms of Doyle’s personal backyard water park.

And the snow thing?

Mystery solved.

“You should close that door,” I said, after Sam had followed me back downstairs into Doyle’s theater.

He hesitated, his bushy brows burdened more with aggravation than curiosity. But he complied. The chatter from the rest of the house disappeared as the door settled against soundproofing gaskets in the jamb.

I stepped across the room. Without fanfare I raised my elbow and pressed on the edge of the movie screen. The frame swung open on its long hinge, revealing Doyle’s portal.

Sam stepped closer and leaned inside. He said, “Holy shit.”

“Yeah.”

Sam did what I had done, although he pulled on fresh latex first. He lifted himself up into the opening behind the movie screen, flicked on the light switch, and stared. I watched his eyes move from the dirt cave, to the angle iron tracks, to the string of holiday lights, to the winch, to the sled.

I couldn’t be sure, of course, but I thought that he was adding things up the same way I had. He didn’t say a word at first; he just shook his head slowly. Admiration? Frustration? Amazement? I couldn’t tell.

After a couple of minutes silently going over the specific elements and the implications of Doyle’s tunnel, he hopped back down from the opening and stood next to me. “This is what you were looking for?” Sam’s voice was only a few decibels above a whisper.

“A tunnel, yeah.”

“But you thought it was in the crawl space?”

“That was my guess. I figured that was most likely. I thought we’d find the opening underneath the plastic in there.”

“You going to tell me how you knew?” he asked.

“No.”

“How did you find it?”

“Boredom. Luck.”

“Tell me how you knew about it.”

“I probably shouldn’t have disclosed the tunnel to you, Sam. I absolutely can’t rationalize disclosing how I know about it.”

For the time being he appeared to accept that. He put his hand on my shoulder, the act of a friend, and said, “Come on. We need to clear out. It’s hurry-up-and-wait time.”

“Why?” I didn’t want to leave; if he’d let me, I was planning to stay and watch the photographers and crime-scene techs do their thing on whatever they discovered in Doyle’s tunnel.

“This isn’t exactly covered by the search-warrant request we made. I have to amend it and go back to Judge Heller.” He paused, filling his ample cheeks with air and exhaling loudly before he spoke again. “And now I’m going to need a fresh warrant for the Millers’ house to see how this thing looks from the other end.”

He sounded weary. “I thought you’d be excited about this,” I said.

“You’re thinking Mallory, right?” He looked back up at the opening in the theater wall. “This is how she got out of her house that night? This is the answer to the snow puzzle?”

“Sure. You have to admit that it adds a whole new dimension.”

“I’ve told you before: The fact that the kid didn’t leave any footprints in the snow the night she disappeared doesn’t mean anything. What’s important about this tunnel isn’t that now we know how Mallory got out of the Miller house. That’s not why the tunnel’s here. What’s important about this tunnel is that now we know how Doyle got into the Miller house.

“What we still don’t know is why. Why did the guy living next door want this kind of access?”

Sam had a point. “He certainly went to a lot of trouble, didn’t he?”

“This is the sort of thing bank robbers used to dig to get into a vault full of cash. But if Doyle Chandler wanted to bust into the Millers’ house to steal, why do all this? People bust into houses all the time. And they get away with it, neighbors even. They pick locks, break windows. But this tunnel wasn’t built for some one-time burglary. This was built for long-term access. Bill Miller never reported a burglary at that house. If Doyle wasn’t stealing from them, why did he want in so badly?”

“Mallory?” I said in reply to Sam’s question.

“Yeah, maybe it’s that simple, maybe he was a perv. Time will tell.”

“What if your underlying assumption is wrong, Sam? What if she didn’t run? What if Doyle took Mallory out through the tunnel? What if that’s why he wanted access to the Millers’ house?”

Sam closed his eyes and his body stilled as though he were narcoleptic and he’d suddenly started sleeping standing up. For a moment even the act of breathing wasn’t apparent. Finally, he opened his eyes and said, “Again, why? There are easier ways, and there’s a lot we don’t know.”

“Like?”

“Like… where does this thing come out in the Millers’ house? Why didn’t we spot it last month? That house got more attention than the new girl at a titty bar.”

“You weren’t looking for a tunnel. I wouldn’t have found this if I didn’t suspect it was here.” I actually didn’t feel like admitting to Sam that what I’d been looking for when I stumbled on the tunnel was Doyle’s fancy remote control. “Who would have guessed that somebody had dug a tunnel into his neighbor’s house? Who does things like that?”

Sam eyed me suspiciously. “You didn’t go down there, did you? To the other end? Tell me you didn’t mess with this evidence.”

“I went no farther in than you did.”

I waited in the vacant living room while Sam went through the house ordering all the search personnel to pack up their equipment and immediately leave Doyle Chandler’s home. While he was upstairs I ambled over to the southern window in the living room and checked to see if I could spot the familiar silhouette in the front upstairs window of the Millers’ house. I couldn’t.