In the bathroom, after Grady squeezed toothpaste on his brush and turned on the cold water, Puzzle suddenly sprang onto the closed toilet seat and sat prairie-dog fashion, watching him with interest. Half a minute later, Riddle ascended to a position on the side of the bathtub, as intrigued as Puzzle appeared to be by their host’s dental-hygiene regimen.

After he finished brushing, they watched him floss. They watched him wash his face and trim a hangnail and wipe splashes of water off the countertop with a towel.

When the time came to toilet, Grady shooed them out of the bathroom and closed the door.

No sooner had he taken the throne than a soft, rapid, irregular rapping arose at the door.

“Go away,” Grady said.

The sound came again: rap-rap-rap, rap-rap, rap, rap-rap-rap-rap-rap.

“I didn’t go out in the yard and stare at you when you were peeing,” Grady reminded them.

Rap-rap, rap-rap, rap-rap-rap-rap-rap-rap.

“Good grief.”

The rapping stopped.

When he heard one of them sniffing along the crack between the bottom of the door and the threshold, he considered renaming them Nosey and Snoopy.

The silence that followed the sniffing was welcome, but then seemed to have a suspicious quality.

Although the skeleton key had long ago been lost, the old door featured a keyhole. Grady leaned sideways on the toilet, lowered his head, and clearly saw a luminous golden eye on the farther side of the keyway.

“You’re a little Peeping Tom. You two ought to be ashamed of yourselves.”

The golden eye blinked.

By the time Grady washed his hands and returned to the bedroom, Puzzle and Riddle were on his bed, lifting his pillows to peer under them.

“Off, off,” he told them.

They dropped his pillows, sat on his bed, folded their hands on their bellies, and watched him.

Having been awakened after such a short snooze, Merlin yawned extravagantly.

Grady went to the empty dog bed, fluffed it, and said to Puzzle and Riddle, “Here. This is yours.”

They stared at him attentively but didn’t leave his bed.

In the closet, where he kept a few dog toys, Grady selected a blue monkey. He returned to the bedroom, knelt beside the empty dog bed, and squeaked the monkey to entice Puzzle and Riddle to come to him.

Merlin grumbled, displeased to be disturbed.

A different toy might possibly lure the pair to their proper place. Instead, Grady decided to show them what was wanted, as he might show a puppy.

He went to his bed and scooped up Puzzle. She not only allowed herself to be lifted and carried, but she also curled into the cradle of his arms, exposing her belly, bending her forelimbs at the elbows and the wrists in an expression of happy compliance.

When Grady put her down in the big fleece-covered dog bed that he intended for her to share with Riddle, he said, “Stay,” as if the commands of canine-obedience school were universally understood in the animal kingdom. He gave her the blue monkey to keep her occupied.

At his bed once more, he scooped up Riddle, who proved to be as cooperative as Puzzle. Grady carried him to his appointed lodgings-where only the plush blue monkey waited.

With Riddle still in his arms, he turned and saw Puzzle on his bed again. He deposited Riddle with the blue monkey and returned to his bed for Puzzle.

She virtually leaped into his arms, nearly knocking him down. But no sooner had he turned to take her to Riddle than he heard the monkey squeaking on his bed behind him.

Merlin no longer grumbled. Head raised, ears pricked, he watched with interest.

Instead of taking Puzzle to the empty bed, Grady put her down beside the wolfhound. He lifted one of Merlin’s sturdy forelimbs and draped it over the golden-eyed animal.

“Stay,” he told Merlin.

In a sterner tone, narrowing his eyes like Clint Eastwood, he issued the same command to Puzzle. He also extended his arm in an accusatory fashion and pointed a finger at her.

She cocked her head to the right.

Grady turned away from her. As he crossed the room to get Riddle and the damn monkey, Merlin and Puzzle sprinted past him and leaped onto his bed.

Riddle put the monkey under Grady’s pillows. With expressions of blissful contentment, the dog and the two somethings curled around one another.

The wolfhound and his posse watched Grady turn out the bedside lamp. They watched him turn out the overhead light.

Leaving on the lamp beside the large Stickley-style reclining chair, Grady went into the closet to retrieve a spare pillow and a blanket.

The snuggling animals raised their heads as he came out of the closet, and they tracked him as he went to the reclining chair. They seemed unmoved by the sour look he gave them.

Grady sat in the roomy chair, which he had built and upholstered the previous year. He stretched out his legs on a matching footstool.

The three compadres watched him solemnly.

He draped the blanket across himself and put the pillow behind his head.

They watched him adjust the pillow and the blanket until he got everything as right as he could. The chair made a comfortable bed, and he was too tired to play here-we-go-’round-the-mulberry-bush with these animated plush toys.

He said, “Just so you know…”

The three caballeros remained interested in him, although he couldn’t honestly claim that they waited with bated breath for what he would say next.

“… I consider this mutiny,” he informed them. “Mutiny indeed. And in the morning, discipline will be administered.”

He switched off the lamp beside the chair.

Their colorful eyes seemed to float in the darkness.

“I see you watching me,” he said.

They didn’t blink.

“I’m counting on you, Merlin. Don’t let them devour me in my sleep.”

At the computer in her office at the veterinary clinic, Cammy Rivers wrote e-mails to Dr. Eleanor Fortney of Tufts University ’s Cummings School of Veterinary Medicine in North Grafton, Massachusetts, and to Dr. Sidney Shinseki of Texas A &M University ’s College of Veterinary Medicine in College Station, Texas. She attached JPEGs of photos of Puzzle and Riddle.

Eleanor Fortney was an eminent zoologist, an internist, and a surgeon who had been a guest lecturer for a month at Colorado State University ’s College of Veterinary Medicine and Biomedical Sciences in Fort Collins, when Cammy had been in her last year of studies at that institution.

As one of the very few CSU students who ever achieved a perfect grade-point average in every semester of her studies, both as an undergraduate and a graduate student, Cammy had been able to receive a guaranteed seat in every one of Eleanor’s small-class lectures but had been invited also to participate in three one-on-one conferences that proved to be some of the most intense educational experiences of her life.

By the time Eleanor completed her month in Fort Collins, she had made a persuasive case that, upon graduation, Cammy should come east to Tufts. Eleanor offered a three-year contract to work in a canine-cancer research project of which she was the director, a program with deep funding provided by an alumnus.

Cammy was tempted by the opportunity to advance her career and contribute to research that might save the lives of countless dogs. But ultimately, she declined. She had dreamed for so long of serving animals not in the research lab, but in the course of their day-to-day suffering; she wanted the satisfaction of healing animals whose names she knew and into whose eyes she had looked.

She and Eleanor had remained in touch, however, and were friends who regarded their work not solely as a profession and primarily as a mission. If Puzzle and Riddle were extreme teratogenic individuals, Eleanor’s broad, deep zoological background might enable her to see through the mutations to underlying characteristics that identified their species.