Grady felt his way cautiously through the living room, from sofa to armchair to armchair, and as he reached the hallway, he heard a thin cry of doggy excitement.

The moth danced with the false flame of the ceiling light, and its shadow swelled and shrank across the pages of the books through which Cammy Rivers searched for answers.

The horses and other animals at High Meadows Farm had seemed no worse for the time they spent in a trance, if indeed it was a trance. But such behavior surely must be symptomatic of a physical disorder.

In her apartment kitchen, above the veterinary clinic, the table was stacked with reference volumes that had thus far failed her. The Internet had failed her, as well, so she put aside one book and opened another to its index.

Absence seizures, in epileptics, weren’t accompanied by abnormal movements. The subject appeared conscious but wasn’t, and the seizure could be mistaken for daydreaming or inattentiveness.

The longest absence seizure, however, lasted less than a minute. The Thoroughbreds and their pets at High Meadows reportedly had been in a trance for more than fifteen minutes.

Besides, none of the animals at the farm had been previously diagnosed as epileptic. And it offended reason to suppose that they would all simultaneously manifest a condition that affected on average one in three hundred individuals.

In addition to congenital cases, other incidences of epilepsy could be attributed to birth trauma and blows to the head, as well as to previous cases of meningitis, encephalitis, and bacterial infections of the brain. Symptoms of those preconditional diseases, however, would have been impossible to overlook. None of the animals at High Meadows-let alone all of them-suffered any such illnesses.

After ruling out epilepsy, Cammy moved on to systemic fungal diseases. She had a dim recollection that certain exotic funguses-not more common varieties like coccidioides-could have brain effects that included absence seizures and hallucinations.

Funguses tended to be regional. But she didn’t limit her inquiry to Rocky Mountain or even Western varieties.

Rare indeed were the funguses that could cause such symptoms. Rarer still were those that conceivably could take hold in four different species-horses, goats, cats, and dogs.

She wasn’t going to consider the duck. She had never treated a duck. She didn’t know how ducks thought or if they thought much at all. The duck was at best a distraction. To hell with the duck.

The problem with pinning the event on a fungus was that none of the animals had exhibited any of the more common symptoms of fungal diseases: diarrhea, fever, chronic cough, difficulty breathing, weight loss, lethargy…

Before leaving High Meadows Farm, Cammy had taken blood samples from seven horses, three goats, and three dogs. In the morning, she would FedEx them to the lab in Colorado Springs.

Considering that none of the animals was suffering and that none had shown any disturbing symptoms other than the communal trance, she would fulfill her responsibilities merely by waiting for the report from the laboratory. But from funguses, she moved on to several thick volumes concerning rare and exotic protozoan diseases.

She had quite literally given her life to healing animals and relieving their suffering. She lived for nothing else. Her patients were her family, her children, her passion, her mission, her only path to peace.

No animal had ever betrayed her. No animal had ever robbed her of her dignity. No animal had ever oppressed and debased her. No animal had ever tortured her.

The shadow of silent wings swelled and shrank across the stacks of books, across the white pages of the open volume, across her badly scarred hands.

Off the south side of the downstairs hall lay the dining room, which Grady had lined with shelves to store the book collection that spilled over from his study. He didn’t need a dining room. He always ate at the two-chair table in the kitchen, and on the rare occasions when he had company for an evening, he invited only one guest.

Following the wolfhound’s cry of excitement, Grady crossed the threshold of the library.

In silhouette, Merlin stood with his paws on the windowsill, as he had in previous rooms.

Grady took three steps before he froze at the sight of what lay beyond the window, unable to make sense of it.

In relation to the house, the moon was farther to the east than to the west, farther north than south. No porch roof overhung this side of the residence, but moonlight was no more able to reach these southern panes than those in the living room.

Suspended as if weightless in the darkness beyond the glass, slightly higher than the dog’s burly head, were four luminous golden spheres, each approximately three inches in diameter, as bright as candlelight but constant in their radiance, without any throb or flicker. Two were side by side on a horizontal plane, and two floated at an angle.

Bubbles, he thought, not only because they seemed to levitate but also because their color was less constant than their brightness. They revealed a subtle iridescence. Shades of gold played through them, and quivers of copper, and streams of silver, much the way that a more complete spectrum of colors manifested across the surface of a soap bubble.

As easy as it was to think of the floating objects as bubbles, he intuited that they were not that ephemeral. They possessed more substance than a first impression suggested.

Although full of light, the spheres seemed to emit none. The panes took no shine from them, and neither did the wolfhound on this side of the glass. The tarnished-silver cedar frame of the window remained uniformly dark. These globes weren’t truly radiant, weren’t luminous in the sense that they shared their light and color, but somehow contained them.

Grady moved toward the window, and as he drew close to Merlin, the iridescence of the objects increased. In two, sapphire washed through the gold, and then many shades of blue at once, and the gold repeatedly bloomed through the other hues, like the base-weave color in a rippling garment of lustrous silk. The third and fourth spheres changed entirely from gold to blues and greens.

The wolfhound continuously expressed excitement and eagerness in a voice pinched so thin that he sounded like a much smaller dog.

As beautiful as the spheres were, their most affecting quality was strangeness. A perpetual aurora borealis in gem-bright colors, captured in weightless globes the size of tennis balls, hovering to no apparent purpose… They seemed to be so far beyond anything in Grady’s experience, so mysterious, so resistant to explanation, so dazzling, that the longer he contemplated them, the more disoriented he became.

He began to feel light-headed and curiously weightless, as though he might suddenly break the bonds of gravity and rise off the floor, float in the darkness on this side of the glass as the four spheres floated in the outer dark.

Then one of the pair blinked, and the other blinked, blinked, and this suggestion of function gave Grady a fresh perspective that resolved the mystery. Eyes. A darkness at the center of each, the irises open wide. Impossibly huge, luminous, color-changing eyes.

The creatures were crowded onto the windowsill. One held its head upright, and the other cocked its head: two eyes aligned on a horizontal plane, two at an angle.

For a minute, the iridescent orbs had so captivated Grady, so riveted his attention, that he was all but mesmerized by them. Now he was able to register the totality of the window, everything that it framed. Dimly, he saw their pale forms, the faintest suggestion of faces, perhaps a forepaw clinging to the casing.