Because he needed both hands to carry the electronic device, Milo could not use the handrail. Watching him descend unsteadily in front of me, I worried that he would fall. Although the treads were sheathed in rubber, the spiral stairs were steep and tightly turned, and bones could easily be broken in a tumble.

“Come on,” I said softly, “let me carry that, Milo.”

“No.”

“I promise not to use it. I won’t turn it on.”

“No.”

“I don’t even know what it is.”

“I remember the vacuum cleaner.”

“That could happen to anyone.”

“Not to just anyone,” he disagreed.

“It wasn’t operator error. The vacuum malfunctioned.”

“Who said?”

“I’m speculating.”

“Lassie had nightmares for months.”

“She’s too sensitive. She needs to laugh at life more.”

“Anyway,” Milo said, “no more stairs.”

At the bottom of the shaft stood a steel door. It could be opened only with the electronic key held close to a key-code reader.

Beyond the door lay the panic room: a fireproof fourteen-foot-square space with a dedicated phone line, a toilet closet, a sink, a bed, and two cases of bottled water.

I snatched up the phone. No dial tone.

“We aren’t staying here,” Penny said. “While he’s searching upstairs, we’re getting all the way out.”

Another steel door offered a second exit from the panic room. When Penny opened it, we were confronted with what appeared to be a blank wall.

This was in fact a tightly fitted pocket door that rolled aside. Beyond lay a utility closet that contained the house’s water softener and filtration system.

Penny led us around the equipment, cracked the door at the front of the closet, reconnoitered the way ahead, and revealed to us the garage that contained the three restored classic pickup trucks and our Explorer.

Milo said, “Cool,” and I echoed his sentiment.

As boy and dog scrambled into the backseat, as I got in the front passenger seat, Penny settled behind the wheel. She handed me the house keys, from which dangled the fob that operated the garage doors.

“Top button, but don’t press it until I tell you. The moment he hears the garage door going up, he’ll come running.”

Milo had buckled himself into his safety harness. I warned him to hold Lassie tight.

Penny released the emergency brake before starting the engine.

She switched on the windshield wipers. As she shifted into reverse, she gave me the go-ahead.

When I thought of Waxx hearing the distant rumble of the roll-up and setting out at a run, that barrier seemed to take forever to get out of our way.

My attention was fixed on the door between the garage and the house, which stood half open, as Waxx had left it. He would come that way, firing at us as he crossed the threshold.

The moment the door cleared the roof of our SUV, Penny peeled rubber backing out of the garage, down the short driveway.

The end of the peninsula had little traffic in the off-season. Penny counted on blind luck as she reversed without hesitation into the street and hung a hard left.

Had I been driving, executing the same maneuver at precisely the same time, we would have struck a car, a skateboarding teenager, someone in a wheelchair, and a nun.

As Penny made that left turn, the luggage in the cargo area rearranged itself with much thumping and rattling, then thumped and rattled some more when she braked to a stop and shifted into drive, but no vehicles collided with us.

Beyond the open roll-up, Shearman Waxx had not appeared in the garage.

The tires spun on the slick pavement, Penny eased up on the accelerator, the Explorer found traction, and we headed up-peninsula.

Just beyond the house, a grape-purple Maserati Quattroporte stood at the curb, engine idling and parking lights on.

As one of the most stylish cars in the world, it would have attracted my attention in any circumstances. I focused on the sleek Maserati now with special intensity because it seemed to me to be as sinister as it was beautiful.

Of course, after the events in the house, everything in view raised my suspicions. Every tree loomed ominously, as if it would collapse upon us. Behind every dark window at every house, a watcher seemed to lurk with malevolent intent. The sky menaced, the gray needles of rain stitched a portentous mood into the day, and the blacktop glistened like a serpent’s scales.

As we passed the Maserati, I looked down at the driver’s-side window from my higher position in the Explorer, and the man behind the wheel gazed up at me.

Heavy protruding jaws, wide crocodilian mouth and thin cruel lips, brutish nose in which the nostrils were as big as nickels, overhanging Frankenstein-monster brow, sunken eyes as pale as those of an albino, eyes that in the somber light of the storm appeared luminous, and overall an impression of tragic malformation: Here was a face met when opening a door or turning a corner in a fever dream, a face materializing from the shadows in the delirium tremens of a chronic alcoholic.