In the nearest corner stood a broom, and I seized it, judging that stiff bristles jammed in the eyes would be as effective as any thrust I might make with a knife, which in any case was not as near at hand as this more domestic weapon and would require a closer engagement with Waxx than I relished.

As the call tone shrilled a third time, I opened the utility-closet door, revealing a twelve-foot-deep, five-foot-wide space with a gas furnace against the back wall. Fluorescent light from the kitchen intruded far enough to confirm that no one crouched in wait for me.

Using the broom, I brushed up the light switch and stepped into the closet as the phone rang a fourth time.

A common gas furnace is to me a mystery of engineering no less complex than a 747 and no less intimidating than a nuclear reactor. My incompetence with mechanisms and machines, and my deep wariness of them, are exacerbated, in the case of a furnace, by the presence of pressurized gas lines.

Yet even I knew that the furnace had not come from the factory with a cell phone epoxied to the face of it, and that in fact no phone had been there previously.

Wires trailed from the phone to a curious construction on the floor, beside the furnace. This ominous assemblage included a digital clock displaying the correct time, several items that I might not have been able to identify even if I’d had time to study them, and what appeared to be a block of clay of the kind with which children played, gray and oily.

On the fifth ring, the display screen lit, and the phone somehow accepted the call. Then it produced—or received—a rapid series of varied tones that might have been a coded message.

On the digital clock, the time changed from the correct 7:03:20 A.M. to the incorrect 11:57:00 P.M.

Even I, ignorant of most things mechanical, knew that our best interests would not be served if we were still in the house when the clock displayed midnight three minutes hence.

Suffering no heroic delusion that I could safely dismantle this device, I backed out of the utility closet and threw down the broom. I raced up the back stairs, shouting for Penny.

As I reached the top of the stairs and stepped into the short arm of the L-shaped upstairs hall, Penny turned the corner from the longer hall that served her studio and the master suite. She carried an artist’s portfolio large enough to hold several paintings of the size that she had lately been creating for The Other Side of the Woods, the book she would publish next autumn.

She said, “Cubby, a phone’s ringing, but it’s not ours.”

Our house had two furnaces, one for each floor. When I pulled open the door of the nearby utility closet and switched on the light, a phone like the one downstairs answered itself; wired to another clay-brick package, it produced a series of varied tones that surely were coded instructions. A digital clock identical to the one in the first closet switched from the correct time to 11:57:30 P.M.

Two and a half minutes and counting.

In spite of her childhood and adolescent experience of colossal destruction, Penny made no attempt to disarm the device but hissed “Waxx” as if it were a curse word, and plunged down the back stairs, two at a time, and across the kitchen, with me so close behind that the toes of my shoes might have scuffed the heels of hers.

Bursting from the laundry room into the garage, she slapped a wall switch, and the roll-up door began to rise.

As I clambered in behind the steering wheel, Penny swung up into the passenger seat, tossed the Explorer keys to me, glanced in the back, and said, “Where’s Milo?”

The dog sat in the backseat, ears pricked and alert, but the boy was gone.