Laura saw the killer raise the submachine gun.

In the main lab, Stefan opened the hinged panel that covered the automatic jaunt-recorder.

A spool of two-inch-wide paper indicated that tonight's uses of the gate had included a jaunt to January 10, 1988, which was the trip Heinrich Kokoschka had made to the San Bernardinos, when he had killed Danny Packard. The tape additionally recorded eight trips to the year A.D. 6,000,000,000-the five men and three bundles of lab animals. Also noted were Stefan's own jaunts: to March 20, 1944, with the latitudes and longitudes of the bombproof underground facility near St. James's Park in London; to March 21, 1944, with the precise latitudes and longitudes of Hitler's bunker; and the destination of the jaunt that he had just programmed but not yet made-Palm Springs, January 25, 1989. He tore the tape, pocketed the evidence, and respooled the blank paper. He'd already set the programming-board clocks to clear themselves and reset to zero when he passed through the gate. They would know someone had tampered with the records, but they would think it had been Kokoschka and the other defectors covering their trail.

He closed the panel and strapped on the backpack that was filled with Churchill's books. He slipped the strap of the Uzi over his shoulder and picked up the silencer-fitted pistol from the lab bench.

He quickly scanned the room to see if he had left anything behind that might betray his presence here tonight. The IBM printouts were folded away in the pockets of his jeans again. The Vexxon cylinder had long ago been sent into a future where the sun was dead or dying. As far as he could see, he had overlooked nothing.

He stepped into the gate and approached the point of transmission with more hope than he had dared entertain in many years. He had been able to assure the destruction of the institute and the defeat of Nazi Germany through a series of Machiavellian manipulations of time and people, so surely he and Laura would be able to deal with that single squad of SS gunmen who were somewhere in Palm Springs in 1989.

Lying paralyzed upon the desert shale, Laura screamed, “No!” The word came out as a whisper, for she didn't have the strength or lung power to make more of it.

The submachine gun opened fire on Chris, and for a moment she was sure that the boy was going to weave his way out of range, which was a last desperate fantasy, of course, because he was only a small boy, such a very small boy, with short legs, and he was well within range when the bullets found him, stitching a pattern across the center of his frail back, pitching him into the sand where he lay motionless in spreading blood.

All the unfelt pain of her ruined body would have been as a pinprick compared to the anguish that wrenched her at the sight of her little boy's lifeless body. Through all the tragedies of her life, she had known no pain to equal this. It was as if all the losses she had experienced-the mother she had never known, her sweet rather, Nina Dockweiler, gentle Ruthie, and Danny, for whom she would gladly have sacrificed herself-were manifested again in this new brutality that fate insisted she endure, so she felt not only the shattering grief at Chris's death but felt anew the terrible agony of all the deaths that had come before it. She lay paralyzed and unfeeling but in torment, spiritually lacerated, at last emotionally broken on the hateful wheel of fate, no longer able to be brave, no longer able to hope or care. Her boy was dead. She had failed to save him, and with him all prospects of joy had died. She felt horribly alone in a cold and hostile universe, and all she hoped for now was death, emptiness, infinite nothingness, and at last an end to all loss and grief.

She saw the gunman approaching her.

She said, “Kill me, please kill me, finish me,” but her voice was so faint that he probably did not hear her.

What had been the point of living? What had been the point of enduring all the tragedies that she had endured? Why had she suffered and gone on with life if it was all to end like this? What cruel consciousness lay behind the workings of the universe that it could even conceive of forcing her to struggle through a troubled life that turned out, in the end, to have no apparent meaning or purpose?

Christopher Robin was dead.

She felt hot tears spilling down her face, but that was all she could feel physically-that and the hardness of the shale against the right side of her face.

In a few steps the gunman reached her, stood over her, and kicked her in the side. She knew he kicked her, for she was looking back along her own immobile body and saw his foot land in her ribs, but she felt nothing whatsoever. “Kill me,” she murmured.

She was suddenly terrified that destiny would try too faithfully to reassert the pattern that was meant to be, in which case she might be permitted to live but only in the wheelchair that Stefan had saved her from when he had meddled with the ordained circumstances of her birth. Chris was the child who had never been a part of destiny's plans, and now he had been scrubbed from existence. But she might not be erased, for it had been her destiny to live as a cripple. Now she had a vision of her future: alive, paraplegic or quadriplegic, confined to a wheelchair, but trapped in something else far worse-trapped in a life of tragedy, of bitter memories, of endless sorrow, of unendurable longing for her son, her husband, her father, and all the others she had lost. “Oh, God, please, please kill me.” Standing over her, the gunman smiled and said, “Well, I must be God's messenger.” He laughed unpleasantly. “Anyway, I'm answering your prayer.” Lightning flashed and thunder crashed across the desert.

Thanks to the calculations performed on the computer, Stefan returned to the precise spot in the desert from which he had departed for 1944, exactly five minutes after he had left. The first thing he saw in the too-bright desert light was Laura's bloody body and the SS gunman standing over it. Then beyond them, he saw Chris.

The gunman reacted to the thunder and lightning. He began to turn in search of Stefan.

Stefan pushed the button on his homing belt three times. The air pressure instantly increased; the odor of hot electric wires and ozone filled the day.

The SS thug saw him, brought up the submachine gun, and opened fire, wide of him at first, then bringing the muzzle around to bear straight on him.

Before the bullets hit, Stefan popped out of 1989 and back to the institute on the night of March 16, 1944.

“Shit!” Klietmann said when Krieger slipped into the time stream and away, unhurt.

Bracher was running over from the Toyota, shouting, “That was him! That was him!”

“I know it was him,” Klietmann said when Bracher arrived. “Who else would it be-Christ on His second coming?”

“What's he up to?” Bracher said. “What's he doing back there, where's he been, what's this all about?”

“I don't know,” Klietmann said irritably. He looked down at the badly wounded woman and said to her, “All I know is that he saw you and your boy's dead body, and he didn't even make an attempt to kill me for what I'd done to you. He cut and ran to save his own skin. What do you think of your hero now?”

She only continued to beg for death.

Stepping back from the woman, Klietmann said, “Bracher, get out of the way.”

Bracher moved, and Klietmann squeezed off a burst of perhaps ten or twenty rounds, all of which pierced the woman, killing her instantly.

“We could have questioned her,” Corporal Bracher said. “About Krieger, about what he was doing here-”

“She was paralyzed,” Klietmann said impatiently. “She could feel nothing. I kicked her in the side, must've broken half her ribs, and she didn't even cry out. You can't torture information from a woman who can feel no pain.”

March 16, 1944. The institute.

His heart hammering like a blacksmith's sledge, Stefan jumped down from the gate and ran to the programming board. He pulled the list of computer-derived numbers from his pocket and spread it out on the small programmer's desk that filled a niche in the machinery.

He sat in the chair, picked up a pencil, pulled a tablet from the drawer. His hands shook so badly that he dropped the pencil twice.

He already had the numbers that would put him in that desert five minutes after he had first left it. He could work backward from those figures and find a new set that would put him in the same place four minutes and fifty-five seconds earlier, only five seconds after he had originally left Laura and Chris.

If he was gone only five seconds, the SS assassins would not yet have killed her and the boy by the time Stefan returned. He would be able to add his firepower to the fight, and perhaps that would be enough to change the outcome.

He had learned the necessary mathematics when first assigned to the institute in the autumn of 1943. He could do the calculations. The work was not impossible because he didn't have to begin from scratch; he had only to refine the computer's numbers, work backward a few minutes.

But he stared at the paper and could not think because Laura was dead and Chris was dead.

Without them he had nothing.

You can get them back, he told himself. Damn it, shape up. You can stop it before it happens.

He bent himself to the task, working for nearly an hour. He knew that no one was likely to come to the institute so late at night and discover him, but he repeatedly imagined that he heard footsteps in the ground-floor hall, the click-click-click of SS boots. Twice he looked toward the gate, half convinced he had heard the five dead men returning from A.D. 6,000,000,000, somehow revitalized and in search of him.

When he had the numbers and doubled-checked them, he entered them in the board. Carrying the submachine gun in one hand and the pistol in the other, he climbed into the gate and passed through the point of transmission-

-and returned to the institute.

He stood for a moment in the gate, surprised, confused. Then he stepped through the energy field again-

-and returned to the institute.

The explanation hit him with such force that he bent forward as if he actually had been punched in the stomach. He could not go back earlier now, for he had already showed up at that place five minutes after leaving it; if he went back now he would be creating a situation in which he would surely be there to see himself arrive the first time. Paradox! The mechanism of the cosmos would not permit a time traveler to encounter himself anywhere along the time stream; when such a jaunt was attempted, it invariably failed. Nature despised a paradox.

In memory he could hear Chris in the sleazy motel room where they had first discussed time travel: “Paradox! Isn't this wild stuff, Mom? Isn't this wild? Isn't this great?” And the charming, excited, boyish laughter.

But there had to be a way.

He returned to the programming board, dropped the guns on the work desk, and sat down.

Sweat was pouring off his brow. He blotted his face on his shirt-sleeves. Think. He stared at the Uzi and wondered if he could send that back to her at least. Probably not. He had been carrying the machine gun and the pistol when he had returned to her the first time, so if he sent either of the guns back four minutes and fifty seconds earlier, they would exist twice in the same place when he showed up just four minutes and fifty seconds later. Paradox.

But maybe he could send her something else, something that came from this room, something he had not been carrying with him and that would not, therefore, create a paradox. He pushed the guns aside, picked up a pencil, and wrote a brief message on a sheet of tablet paper: THE SS WILL KILL YOU AND CHRIS

IF YOU STAY AT THE CAR. GET AWAY. HIDE. He paused, thinking.

Where could they hide on that flat desert plain? He wrote: MAYBE IN THE ARROYO. He tore the sheet of paper from the tablet. Then as an afterthought he hastily added: THE SECOND CANISTER OF VEXXON. IT'S A WEAPON TOO.

He searched the drawers of the lab bench for a glass beaker with a narrow top, but there were no such vessels in that lab, where all of the research had been related to electromagnetism rather than to chemistry. He went down the hall, searching through other labs, until he found what he needed.

Back in the main lab, carrying the beaker with the note inside it, he entered the gate and approached the point of transmission. He threw the object through the energy field as if he were a man stranded on an island, throwing a bottled message into the sea.

It did not bounce back to him.

-but the brief vacuum was followed by a blustery inrush of hot wind tainted by the faintly alkaline smell of the desert.

Standing close at her side, holding fast to her, delighted by Stefan's magical departure, Chris said, “Wow! Wasn't that something, Mom, wasn't that great?”

She did not answer because she noticed a white car driving off state route 111, onto the desert floor.

Lightning flared, thunder shook the day, startling her, and a glass bottle appeared in midair, fell at her feet, shattering on the shale, and she saw that there had been a paper inside.

Chris snatched the paper from among the shards of glass. With his usual aplomb in these matters, he said, “It must be from Stefan!”

She took it from him, read the words, aware that the white car had turned toward them. She did not understand how and why this message had been sent, but she believed it implicitly. Even as she finished reading, with the lightning and thunder still flickering and rumbling through the sky, she heard the engine of the white car roar.

She looked up and saw the vehicle leap toward them as its driver accelerated. They were almost three hundred yards away, but were closing as fast as the rough desert terrain permitted.

“Chris, get both Uzis from the car and meet me at the edge of the arroyo. Hurry!”

As the boy sprinted to the open door of the nearby Buick, Laura raced to the open trunk. She grabbed the canister of Vexxon, lifted it out, and caught up with Chris before he had reached the brink of the deep, naturally carved water channel, which was a raging rivet during a flash flood but dry now. The white car was less than a hundred and fifty yards away. “Come on,” she said, leading him eastward along the brink, “we've got to find a way down into the arroyo.”

The walls of the channel sloped slightly to the bottom thirty feet below, but only slightly. They were carved by erosion, filled with miniature vertical channels leading down to the main channel, some as narrow as a few inches, some as wide as three and four feet; during a rainstorm, water poured off the surface of the desert, down those gulleys to the floor of the arroyo, where it was carried away in great, surging torrents. In some of the down-sloping drains the soil had washed away to reveal rocks here and there that would impede a swift descent, while others were partially blocked by hardy mesquite bushes that had taken root in the very wall of the arroyo.

Little more than a hundred yards away, the car strayed off the shale into sand that pulled at the tires and slowed it down.

When Laura had gone only twenty yards along the edge of the arroyo, she discovered a wide channel leading straight down to the floor of that dry river, unobstructed by rocks or mesquite. What lay before her was essentially a four-foot-wide, thirty-foot-long, water-smoothed, dirt slide.