As the doors closed, Julian said, “What kind of contamination? You still haven’t said.”

“I’m no medical scientist, Julian. If I tried to explain it, I’d only make an idiot of myself. Dr. Lightner will lay it out for you.”

The elevator was already descending when Jean-Anne said, “John, I think the blood lab is on the main floor.”

“Yes, it is. But Dr. Lightner has set up a second testing station in the basement to speed things along.”

The elevator doors opened, and they stepped into the corridor. John Martz turned right, with Jean-Anne at his side and Julian a step behind.

A strikingly handsome young man came out of a room on the left. His looks were so singular that Jean-Anne thought he must be someone famous, perhaps someone she had seen on TV.

She glimpsed a few peculiar objects in the room beyond him: what seemed to be bags made of a silvery fabric, hanging from the ceiling, approximately pear-shaped and evidently filled with something heavy.

Then the young man closed the door behind him, and John Martz led them farther along the corridor as he said, “It only takes a few minutes to get the test results. And they’re gentle with the needle.” He held up a thumb. “Can’t even see where they pricked me.”

Jean-Anne thought she might have seen the young man on American Idol. She glanced back, but he had disappeared.

John Martz ushered them into an unfurnished room in which sat five patients in wheelchairs. Closing the door and remaining beside it, he said, “It’ll only be a minute.”

Of the patients, three were strangers to Jean-Anne. The others were Lauraine Polson and Susan Carpenter.

Lauraine, a waitress at the Andy Andrews Café, had been admitted on Monday with a severely prolapsed uterus. She was supposed to have had a hysterectomy this morning. The previous evening, Jean-Anne visited her, bringing a book of crossword puzzles, to which Lauraine was addicted, and a small basket of fresh fruit.

“Dear, you didn’t have surgery?”

Lauraine grimaced. “It’s annoying, but there’s nobody to blame. There’s a shortage of surgical nurses because of the flu. I’ve been rescheduled for tomorrow.”

“Until tonight, I haven’t heard anything about the flu going around,” Julian said.

“It’s hit a few of our guys in the department,” John Martz said.

Susan Carpenter, a beautician at Rosalie’s Hair and Nails, indicated the semitransparent Tupperware container in Jean-Anne’s hands. “Are those your mini muffins, Jean-Anne, like you brought us at the shop last Christmas? I usually don’t like muffins but they were fabulous.”

“These are for my sister, dear, and low-fat. She’s held over from gallbladder surgery for intravenous antibiotics, since it was badly abscessed. I didn’t know you were here, or I’d have brought you some.”

“They just checked me in this afternoon.” Susan pointed to the wrapped paperback that Julian held. “I love that giftwrap.”

“Mary-Jane is crazy for cats,” Julian said.

“I know she is,” Susan said. “I didn’t think she’d ever get over losing Maybelle.”

“I don’t think she really has,” Julian said.

The door opened, and into the room came a different young man from the one in the corridor a minute earlier. Remarkably, he was even more handsome than the first, his face so compelling that again Jean-Anne felt sure he was somebody.

In the service room at the top of the stairs to the hospital roof, Travis consulted his wristwatch and said, “It must be dark enough now.”

Bryce Walker wasn’t yet chilled to the bone, but he was cold enough that he wanted to get moving.

From a wall hook, he took down a broom. Before opening the outer door, he switched off the lights.

Because of the overcast, the bleak October heavens appeared nearly as dark at the start of twilight as they would be at the end. In the stillness of the evening, the low cloud cover was as motionless as a painted sky.

Travis stepped out onto the roof. Bryce followed him, laying the broom handle across the threshold to prevent the door from falling completely shut.

The outer door would lock automatically. Although the hospital might be enemy territory, Bryce wanted the option of retreat.

Here and there across the vast flat roof stood several shedlike structures similar to the one they had just left, some with slatted and screened walls, others with solid walls. A couple of them housed head mechanisms for the elevators and provided service access. Bryce didn’t know what the others were.

Hooded vent pipes and ducts of different sizes rose one or two feet above the roof. In the fading light, they resembled clusters of mushrooms.

Each of Memorial Hospital’s three wings featured a sturdy steel ladder bolted to the brick wall, to provide firemen with access to the roof by other means than the hydraulic tower ladder on their truck. Descent along the north wing or the main wing would be too public, but the third ladder, which was the farthest from their current position, allowed a discreet escape down the relatively secluded southern face of the building.

As long as they traveled close to the center line of the building, the width of the roof and the three-foot-high parapet wall would prevent them from being seen by anyone on the grounds below or out on the street.

Bryce said to the boy, “The attic is directly underfoot, with no one there to hear, but let’s be light-footed anyway. Stay close.”

“All right.”

“Be careful of the vent pipes.”

“I will.”

The handsome young man moved with the grace of a dancer and the self-confidence of a star. He stopped at the center of the room. The five patients in wheelchairs waiting for their blood tests, Jean-Anne Chouteau, and Julian Vergelle were in a semicircle around him.

When he smiled at them, his beauty seemed otherworldly. Jean-Anne saw that she was not the only one whom he enchanted. Even Julian stared as if transfixed.

Although she didn’t know this man and although she would be disappointing Mary-Jane, Jean-Anne wanted to give him the Tupperware container full of her admired mini muffins.

Before she could offer the baked goods, the young man said, “I am your Builder.”

She had no idea what this meant, but his voice was mellifluous, of such a pleasing timbre and so sweetly flowing that she wished that she could hear him sing.

He turned to Lauraine Polson and stepped closer to her.

When he extended his right hand toward the waitress in the wheelchair, she smiled uncertainly but then reached out to him, almost as if he were inviting her to dance and she intended to accept.

Something happened to the young man’s hand before Lauraine could take it. First the fingers and then everything up to the wrist seemed to dissolve, as if his hand were composed of thousands, maybe millions, of gnats that had conspired to imitate a hand but that were no longer able to do so convincingly. They maintained the shape of a hand, but the skin was gone and the fingernails, and the wrinkles at the knuckles. The hand was smooth and silvery, yet the substance of it seemed to be a ceaselessly swarming mass of tiny insects, their thousands of iridescent wings glittering as they furiously beat, beat, beat against the air and one another, though they were nothing as ordinary or as innocuous as insects.

Lauraine reeled back in her wheelchair, but the young man leaned forward to place his hand atop her head, as if she were a supplicant and he a tent revivalist, a faith healer calling down the power of God to make her whole.

But then at once his hand sank into her head, through her skull, as if her bone were butter, onward into her brain, whereupon she violently kicked the foot braces of the wheelchair, her arms flailed spastically, but only for a moment before she went limp. Her eyes fell backward in her sockets, out of sight, a silver horde swarming where her eyes had been, and her mouth dropped open to spew forth not blood—as Jean-Anne expected—but a buzzless hive of minute wasps, though not wasps, and this devouring multitude churned upward, dissolving the shell of her face, still with not a spurt or spot of blood.

Jean-Anne didn’t realize that she had moved until she backed into the wall, knocking a sharp shivering pain from the nerve that transited her left elbow.

Julian threw down the flowers, the kitten-wrapped paperback, and bolted past her toward the door.

She wanted to flee with him, but she seemed pinned to the wall by her elbow pain, nailed to the floor by the heels of her shoes.

John Martz had a nightstick, and he swung it at Julian’s head, landing a blow of such power that the sound of it was like a baseball bat cracking a home run out of the park. Julian dropped in a heap, and John Martz bent over him, hammering his head with the nightstick, John Martz whose wife was a Red Hat lady, John Martz who was so funny as the auctioneer at the annual hospital gala, hammering, hammering with a gleeful ferocity.

The handsome young man’s face was a mask of fierce rapture as he seemed to reach his right hand down into the stump of Lauraine Polson’s neck, like a magician reaching into a top hat to pull forth a rabbit. He thrust his arm down into her as far as his elbow, her body began to collapse inward as if deflating, the young man began to swell as if Lauraine’s substance was now part of him, his head grew misshapen, his face ballooning into a leering demonic apparition. All over his body, a shimmering silver haze arose, the whole of him churning as his hand had churned, as if he were entirely composed of billions of tiny winged piranha mimicking the human form.

One of the patients Jean-Anne didn’t know, a bald man with a red mustache, had leaped up from his wheelchair, had staggered toward the door. He tried to fend off John Martz, but the nightstick broke his fingers and then broke his face. Looking up from the dead or dying man, John Martz grinned at Jean-Anne from across the room and shook the club at her, saying, “You want some of this? Come get it. You want some?”

Having abandoned her wheelchair, Susan Carpenter huddled in a corner, and the two other patients were in a different corner, all of them screaming or crying out for help.

Jean-Anne wanted to scream, she kept trying, she couldn’t make a sound, she couldn’t move, she could only stand there holding the container of mini muffins, holding it in front of her, gripping the Tupperware with such force that her fingers dimpled it, presenting it as if the muffins were an offering to appease the savage god that had abruptly manifested from the young man, but this malevolent deity wasn’t satisfied with prizewinning muffins, he wanted more than what had pleased the judges at the county fair, he wanted much more from her, he wanted everything.

As if mocking the screams of his waiting victims, the greatly deformed young man, no longer handsome by any standard, opened his mouth wide, and from within him rippled forth thick silvery ribbons. As they lapped across Jean-Anne’s face and she went blind in an instant, she remembered the large silvery fabric bags, pear-shaped, filled with something heavy, hanging from the ceiling, and now she thought, as her last thought: Not bags. Cocoons.

Nearing the southern end of the roof on the main wing, Bryce heard faint cries like those he had listened to at the return-air grille in the bathroom.

Travis heard them, too. He grabbed the sleeve of Bryce’s robe. “Wait. What’s that?”

“What I heard before.”

“It’s coming from over there.”

“There’s no one on the roof but us.”

“Over there,” the boy repeated.

“Don’t let it into your head, son. Come on.”

“No, wait. Just wait.”

The boy wove through an obstacle course of vent pipes, cocking his head this way and that until he identified the source. He dropped onto his knees to listen.

The voices rose from such a distance, through fibrous filters and past the slowly rotating blades of exhaust fans, through so many turns of insulation-wrapped duct that they were thin and faltering. Yet the misery and terror they expressed were so affecting that Bryce shivered more because of those faraway cries than because of the cold air.

The boy said, “It’s not a TV.”

“No, it isn’t.”

“They’re real. They’re real people.”

“Don’t listen. Come on.”

“Are they being killed?” Travis asked.

“Don’t listen. You’ll never stop hearing them.”

“We’ve got to help them. Can’t we help them?”

“We don’t know where they are,” Bryce said, “except probably in the basement.”

“There must be a way down there, past the guards.”

“No, there’s not.”

“There’s got to be a way,” the boy insisted.

“I know that’s how it seems, that there’s got to be, but sometimes there’s just not.”

“It makes me sick to hear it.”

“If somehow we could get to them,” Bryce said, “then we’d be in the same trouble they’re in now. It would be our voices echoing up the pipe.”

“But it’s horrible, just to let it happen.”

“Yes. Come on now.”

“What is happening to them?”

“I don’t know. And we don’t want to find out firsthand. Come on, son. Time may be running out for us here.”

Reluctantly, Travis rose from the vent pipe and rejoined Bryce.

When Bryce put a hand on the boy’s shoulder, he could feel him shaking.

“I like your spirit, Travis. You’ve got a righteous instinct. We can’t save those people. They’re already dying. But if we can get help and learn what’s going on, maybe we can save others.”

“We’ve got to.”

“We’ll try.”

The roof of the main wing became the roof of the south wing. Bryce found the fire ladder curving up and over the parapet just where he thought it would be.

The sky was a field of vaguely phosphorescent ashes, darker in the east than in the west, but dark to one degree or another from horizon to horizon.

Leaning over the parapet with Travis, Bryce could see a paved fire lane that ran along the side of the building, illuminated by evenly spaced curb lamps. He could not see much of the grassy descent that receded beyond the curb, but he recalled the contours of it from his death-watch walks on this roof. The slope led to a copse of pines visible only as conical forms silhouetted by distant streetlamps and house lights.

“Windows to each side of the ladder. Don’t worry about them,” Bryce said. “Looks like about thirty feet to the bottom, maybe a little more. Are you okay with it?”

“Sure. I can do it.”

“That’s an emergency-only lane. It’s not used by staff or for deliveries. There’s not much chance anyone will come along and see us, so you don’t have to go down as if it’s a greased pole.”