The thump was a stranger, and it scared her.

Only then did Cate pick up her watch from the nightstand and look at the time. It was 4:06. The streetlights reflecting off the dense fog had lent the sky an eerie luminescence, feigning sunrise and providing a false dawn.

4:06.

Cate stared at the dial, anger and fear welling up in her in equal parts. No workman showed up at a job site at 4:06. Even Bob Vila didn't go to This Old House until six-thirty at the earliest! Suddenly, she was wide awake, her senses honed, her radar on full alert. She could smell the oil from the cement mixer parked out front. She could hear the ticking of her watch, the hum of the PC on her desk. The screensaver ran on a loop reading, "John Galt is dead. John Galt is dead." Her capitalist manifesto.

Someone she did not know was inside the house. There was an intruder in her study. Call the police. She reached for the phone, but froze halfway there, paralyzed by an older and more wrenching fear. There were worse things than physical peril.

Retrieving her hand, she slid her back against the headboard and waited for a footfall on the landing, for the door to her bedroom to be flung open. For a few moments, the house was silent, and Cate decided it was better for you to go get them than for them to come get you. Gathering her courage, she placed her feet on the ground and stood. For once, she'd make impatience her strong suit. She took one step and stopped, but only for a moment- just long enough to double-check if her sanity was in its proper place, tucked between her aversion to cigarettes and her love of Vermeer- then padded across the room to the bedroom door. The wood planks were cold to the touch and groaned at her meekest step.

Slowly, she ordered herself, concentrating on rolling her feet from heel to toe. You're a Shaolin priest walking on rice paper, she said, quoting from the bible of late-afternoon TV. Calmly, Grasshopper. But to her revved-up ears, she sounded like a newly shoed colt crossing the smithy's floor.

Cracking open the door, she peered to her right and left. The landing was empty, dusted with a sheen of plaster that glowed in the dark like some phosphorescent algae. There were no lights on in the house. Advancing on the staircase, she began to get the motion right, heel to toe, rolling her foot, and her tread fell as delicately as a doe's.

But if her steps were controlled, her mind was running full tilt. She remembered that she hated living alone and cursed herself for moving out of Jett's four-thousand-square-foot home in Pacific Heights. At the same time, she reminded herself she'd had no choice, even though leaving had been the hardest thing she'd ever done.

Continuing her spate of recriminations, she turned to the alarm system- or more specifically, to her practiced nonchalance about turning it on at night. What was the point? With so many workmen traipsing in and out of the house at all hours, it was better to keep an open door. Besides, it was hardly as if there was much to steal: a ten-year-old TV, a few silver candelabra, a stereo she had yet to hook up since her return to singledom.

Her neighborhood on the fringes of Haight-Ashbury wore its poverty like a genteel curse. Rusted VW vans, twice-repainted Olds 98s, SS Camaros with fat racing stripes running across their hoods, lined the curb, their bumper stickers badges of membership to a bygone era. "Drop in, Turn on, Tune out," "Age of Aquarius," and her favorite, "Keep on Truckin'," with the magnificent Crumb icon strolling along flashing the peace sign. On a sunny Saturday afternoon you couldn't pass two houses without hearing Mason Williams's "Classical Gas" or catching the scent of Colombian Gold wafting from an open window.

But you didn't put in the alarm to protect your possessions, a wise voice reminded her. You installed it to protect yourself. You always knew they would come. You should have known it would be now.

Laying a hand on the banister, she began her descent. There were fourteen steps to the first floor, the lower six sick with termites. With every step, she craned her neck farther over the rail, curiosity winning over fright as to what or whom she might discover.

Ka-thunk!

Cate stopped cold, frozen so still she might have been geologically petrified. Silhouetted against the ivory wall, her figure was slender, well-proportioned, and if ten pounds heavier than she would have liked, the more fit for it. She ran three times a week, made it to Pilates every Saturday morning, and ate enough Cherry Garcia to make it all for naught. She liked to think of herself as strong and capable, but alone in her house at 4 A.M. the opinion seemed boastful and ridiculous. Refusing to budge, she asked herself who it could be banging away in her study so contemptuously, who the interested party was who was practically daring her to come down and ask what the hell was going on.

Again she entertained the notion that it was a burglar, but she knew better. Nor could she bring herself to believe it was a rapist, a psychopath, a deviant, even a garden-variety lunatic trying to lure her downstairs to have his way with her. It was none of them. Or anyone else, for that matter, who might have randomly chosen her home to break into on this damp, foggy night.

She knew why there was someone in her house and she knew what they were looking for. She had known for some time that her existence could no longer be accepted with a tolerant grunt or dismissed with a paternal wave. Not with events moving as quickly as they were. It amused her that some people might think her dangerous. Cate Magnus, graduate of the East Coast establishment: Choate, Georgetown, Wharton. She, the failed painter, exiled executive, sucker for beat-up Jeeps and obscure French films. The reporter with a dozen great ideas for books and never the tenacity to complete an outline, the lifelong fugitive from romantic misadventures. Why should anyone be afraid of her? She was someone whose fingers felt more comfortable teasing the keys of a computer than the trigger of a gun.

Cate stared at the pistol in her hand, dull, gray, and bluntly menacing. For the life of her, she could not remember fishing it from the cache on the side of her bed. She noticed, too, that she was wearing her panties and nothing else. Great. Get the gun, but forget your clothes. Show 'em your boobs, then shoot.

No, countered the wise voice again. You're still fooling yourself. You're a searcher, a collector, a seeker of the truth. You are a woman with a vendetta and the means to exercise it. In fact, you're very dangerous. Never more than now, and you know that, too. As for the gun, don't be coy. You trained five nights a week for a year so that you could hit a nickel at twenty paces. Why did you steal it from your boyfriend's house if not to use it?

The thud came again. Ka-thump.

Suddenly, she knew what they were doing. There were two of them. There were always two. They were trying to get into her safe, the little fireproof model she'd picked up at Home Depot to protect her zip drives and her journals against fire. They were lifting it and dropping it or banging something on top of it in some brutish attempt to pry it open.

Cate reached the first-floor foyer. At the end of the hall, the door to the study was shut, a light burning beneath the crack. She advanced a step, holding the gun in front of her. They really were insolent, she thought, praying anger would fuel her courage.

Something warm and feathery brushed against her leg, and Cate nearly jumped out of her skin. She wanted to scream, but found her heart already lodged in her throat. She looked down and stifled a shrill note of terror.

It was Toby, her gray Angora. Toby, the meowing mauler of Menlo Park, whom she'd threatened to get rid of a hundred times because the damned kitty never shut his mouth. "Shh, Toby." She reached down to pet him, but he was already gone, bounding upstairs to doze in the folds of her duvet. "Coward," she hushed after him.