At eight o'clock Macklin switched off the flourescent lamp over his bench at the remote end of the laboratory and wearily eased himself out of his white overall. Young Carson, working quietly at the prototype test panel, eyed him with a certain degree of curiosity. Macklin looked tired; his eyes, normally dark and deep-set, were even more recessed than usual, and his shoulders hung at an apathetic slant, as though the bones beneath the creases of his worn gray suit had begun to melt.

"Finished, Doc?" asked Carson.

Macklin did not reply immediately. He picked up the sheets of foolscap paper scattered on the bench and thoughtfully flicked through them with the air of a man scanning a newspaper for lurid headlines; then, satisfied with the neat and almost prim arrangement of formulae and minutely written text, he carefully inserted them in a green cardboard folder. So much for dimensional quadrature for tonight, he told himself. It was a subject that demanded undivided attention, and at the moment--well, there were other problems absorbing too much of his limited reserve of nervous energy. Unscientific problems. Problems, in fact, that knocked the stuffing out of a man far more than the most arduous and intensive scientific research.

He placed the file in a steel locker above the bench, then turned the key. And at that point Carson's question, already eight seconds old, registered itself on his brain.

"Nowhere near finished," he replied, speaking with a vaguely preoccupied air. "The fact is I've got a brute of a headache, and anyway there are still two days until the final tests."

The younger man nodded sympathetically at the panel. He had already forgotten about Macklin, and wasn't really listening.

"I haven't been sleeping too well recently," Macklin went on, anxious to prove his point. Strange how he couldn't even tell a simple lie without feeling vaguely guilty and immoral. That was his trouble--too many damned high-minded principles that made him critical of his every word and deed, as though some inner radar eye were continually monitoring his behavior. But it wasn't entirely a lie about the headache. In a way he was speaking the truth: there was a headache--not a physiological one, perhaps, but a headache for all that--waiting for him when he got home. Hadn't he lain awake at night for more weeks than he cared to remember, wondering about Lydia, studying the monochrome pattern of her face as she slept in the darkened room, trying to interpret the unguarded words and incidents that for some time had been warning him of the imminent breakup of their marriage, not yet four years old?

"You ought to take a holiday," Carson was saying. He adjusted a milled control knob and concentrated on the scarcely visible flicker of an indicator needle. "This is a depressing place at the best of times and you can have too much of it." He spoke as though he were reading lines out of a book.

Macklin shrugged his shoulders in what was meant to be a nonchalant gesture. "Perhaps you're right," he said. Slowly he walked past the assembly bench. "Well, good night."

"Good night," murmured Carson, without looking round.

There was something depressing about "D" Block, Macklin thought. Something divorced from the pleasanter side of life, with a kind of inherent portent, like a dentist's waiting room, or the purposive austerity of a police station. For one thing, the block was built underground, like a fortress, and the air was still and sluggish except where the ventilators stirred into a localized maelstrom of motion. The three-phase flicker of the blue-white strip lighting threw everything into garish stereoscopic relief and played tricks with the eyes--like an old movie. The walls and 2 doors vibrated ceaselessly with the thin attenuated whine of the generators in the adjacent power room.

Carson was right, he decided. He needed a holiday, and so did Lydia. Everything would be all right between them if they could go away for a holiday, he was convinced of it. Somewhere remote from telephones and traffic and newspapers where they could get to know each other all over again. He would fix it. As soon as the preliminary tests on dimensional quadrature had been completed he would tackle Bressler about it. There wouldn't be any difficulty. Bressler had absolute confidence in him and didn't need to be reminded of Macklin's stubborn application to the research program, of the many nights he had spent in the laboratory when he should have been at home playing the part of husband instead of scientist. He was entitled to a holiday, and he would damn well see that he got it.

The floor space of the laboratory, some forty feet in length, was relatively empty. As he walked towards the far door the faint clinking echo of his footsteps on the hard plastic-surfaced ground created a transient ghostly effect. The small atomic turbine standing idly on its bare trestle attracted his glance for a few seconds. It looked smooth, almost sinister, with a suggestion of tremendous latent power lurking under the cold curved steel of its shell, except where the drive shaft was partly stripped for torque tests. Beyond that, nearer the door, was the recessed lead-walled cubicle with the large electronic control panel resembling the cockpit of a stratosphere air liner, used for operating the robot hand that manipulated the uranium isotopes and other radioactive elements employed in the research program. And finally, standing on a raised platform like a museum exhibit or a piece of surrealist sculpture, he saw the capsule itself, nearing completion.

Macklin's eyes, wandering affectionately over its polished disclike form, and taking in the intricate instrumentation visible through the long rectangular window, held a sneaking glint of satisfactiona glint that was playing truant from the cool, rational, dispassionate chamber of the brain in which it was normally kept locked. The truth was that he couldn't help feeling just a little proud. This was the true process of creation: from the abstractions of the mind, expressed in mathematical formulae, to the geometrical beauty of the solid object. From the conception to the materialization.

He wondered idly whether his fellow scientists were ever human enough to enjoy, as he did, the end product of a prolonged mental pregnancy. Or was he being unscientifically sentimental?

Benson was inside the capsule, lying flat on his back, spot-welding part of the internal structure. Outside, standing behind it, was old Ettinghausen, his crisp gray hair and wide glistening eyes visible over the flat circular top of the machine. He nodded in greeting as Macklin passed by, then turned his eyes downwards to some unseen task.

Macklin passed through the door into the long gray corridor, but his thoughts were still in the laboratory, critically visualizing the layout of the capsule cabin as though seeking some hidden flaw in the design which could be rectified even at this late stage in development. It was the habitual inquisitive probing of a trained scientific mind, the kind of mind that insisted on adding a question mark to every bland statement of fact.

He walked down the corridor automatically as he had done a thousand or more times before. At the massive steel door that looked like the entrance to a bank strong room he returned mentally to the here and now, and pressed a luminous button on the wall. The door slid aside with a faint sighing sound, revealing the square cavity of a lift. He stepped inside and pressed the switch; immediately the door closed again, and he felt the floor pressing upwards against his feet as the cubicle ascended to ground level, leaving the honeycomb of rooms, offices, workshops and laboratories buried deep in the ground beneath ten feet of reinforced concrete.

On the surface he passed through the security check point, where the uniformed guard glanced at his familiar features with shrewd alertness and made a checking-out entry in the register, and then through the Geiger post where he stood still on a circular plate set in the floor while an overalled technician quickly ran the radiation detector over his body.

And then he was in the open air, under the fading daylight of an October sky, walking over crisp gravel and feeling the pleasant contact of fine rain on his face and hands.

His feet crunched over the yellow gravel to the first of he barbed-wire fences bounding the perimeter of the site, from here it was possible to appreciate the vast extent of the place. "D" Block, hidden beneath the ground, was only one small unit in this restricted zone with its forest of huts and rows of glass-roofed factorylike buildings, interspersed with giant reinforced structures housing the atomic piles and the isotope stores, and fringed by squat circular blockhouses peering blankly outwards through the perimeter wire.

At the main gate, with its second security check point and guard room, a tall notice board announced in bold black lettering: MINISTRY OF SUPPLY EXPERIMENTAL SITE. POSITIVELY NO ADMITTANCE WITHOUT AUTHORIZATION.

He showed his permit to the duty officer as regulations required, returned the salute with a perfunctory gesture of his hand, and walked out into the free unrestricted Essex countryside.

On the right was the parking lot. His feet led him instinctively to the tarnished shape of the prewar Ford which had faithfully and unerringly carried him twice daily between the site and the satellite town of Brant, where paraded lines of slick semidetached villas housed the five thousand workers and staff of the atomic plant. He eyed the car with a certain amount of warmth; it wasn't much to look at, and was undoubtedly outshone by the majority of sleek streamlined vehicles lined up on either side, but the engine was good, and--well, after so many years it had become something of an old friend.

He climbed in, revved up with methodical deliberation, then backed slowly out of line. Presently he turned on to the main road leading to Brant and watched the speedometer needle creep round to a steady fifty. Home in seven minutes--rain or no rain.

There were fresh car tracks in the wet earth outside Number 4 Einstein Avenue (all the roads in Brant were named after scientists) and the square pattern of the treads had not yet dissolved into mud. Macklin filed this fact with other data in the appropriate pigeonhole of his mind. It wasn't the first time it had happened; even in the descending darkness of evening and through the semiopacity of the dust-coated windscreen he could see that the tracks were the same as last time--and the time before that.

Mechanically he stepped out of the car. The road surface was sandy, stony ground, bulldozed and compresses by a team of relentless steam rollers into a temporary semblance of a path. In due course a concrete surface would be laid, but Brant was a young town and developments had to take place in a predetermined order of priority.

He opened the double gate and the garage door, then got back into the car and drove straight in, switching off the ignition with a slow tired twist of his fingers. Then he walked round to the front door, dragging on the key chain in his trouser pocket until a bunch of keys slipped suddenly into his hand. Feeling cold, damp and preoccupied, he let himself into the house.

There was no sign of Lydia downstairs, but from above came the sound of splashing water and he knew at once that she was taking a bath. Soft dance music filtered through the door of the lounge. He entered the room hesitantly as though expecting to find an unwelcome guest reclining in one of the easy chairs, but the room was empty and the radio had been left switched on. A faint acrid odor hung in the air, but he was unable to identify it immediately.

Thoughtfully he switched off the radio, and caught sight of his reflection in the hexagonal mirror over the fireplace. He found himself looking at a tall, saturnine individual of pale complexion, with dark green almond eyes. Those eyes worried him sometimes: they looked as though they had been dropped into his face while hot and had burned their way deep into the cavity of his skull. And because they were so much withdrawn from the outer world they seemed to possess an uneasy sensibility of their own, but he knew that it was just an illusion. His profile was all right--not in the best classical mold, perhaps, but all right. Quite scientifically cast.

There was, however, an unfamiliar droop to the thin line of his lips and the black hair hung limply over his right eye. He swept it into place with an impatient motion of his hand. The image in the mirror did likewise.

Then, without quite knowing why, he moved closer to the glass, studying the silver-gray streaks above his temples and the lines beneath his eyes. They were the telltale signs that dated his features and pronounced his age at more than thirty-five. Thirty-eight, to be exact. Nearly forty. The numbers produced no reaction in his brain; he was far too rational to feel sentimental about the passing years. Besides, a man wasn't fully mature until he reached forty--not mentally mature--and it was the mind that really mattered. The body was simply a shell.

His eyes turned to the empty fire grate and focused upon a few fragments of gray substance on the bars, near the wall. On an impulse he stooped down and scrutinized it carefully as though it were a brand new isotope with unsuspected properties, and noted that it was dark in color and granular in parts. The dust was striated, as though the bars had been recently swept with a stiff brush.

By now his curiosity was thoroughly aroused. He went down on one knee and pulled the chrome front from the grate. The space beneath the bars was dark, so he struck a match and by its flickering light inspected the dust and dirt on the fire-clay foundation of the hearth.

His first suspicions were confirmed: the bars had obviously been swept, and among the sweepings was more of the dark gray ash containing, as he had anticipated, one or two dark brown fibrous strands. Abruptly he was able to name the strange odor in the air of the room--it was the tang of pipe tobacco. Somebody had been smoking a pipe and had tapped the ash into the grate, after which the bars had been carefully swept. For what purpose? To remove evidence? Evidence of what?

Temporarily satisfied with his discovery he stood up, surveying the room with morbid interest. The cocktail cabinet in the corner by the window drew his attention next; it stood open, with the internal light glistening from the crystal surface of the glasses. He crossed over to it with slow measured tread, feeling vaguely like a Scotland Yard detective, and poured himself a straight whisky. Then, with the fiery liquid burning his throat and exerting its usual analgesic effect on his stomach, he inspected the contents of the cabinet. His instinct had not betrayed him for two of the wine glasses had been used recently, and the remaining drops of a liqueur formed tiny cerise pools above the stems.

Just one more fact for the growing collection, but it was not yet time to start adding them up. No doubt Lydia would explain it all with persuasive facility--if she felt affable enough. He would put it to her subtly, with a shrewd application of psychology, noting her reaction for analysis at a later stage. That was the true scientific approach; none of the cheap emotional recrimination for him. There would be no bother and no argument.

He smiled thinly and poured himself another whisky. He felt confident now, and a little superior, because he knew something that Lydia didn't know he knew. The pipe and the drinks. Another man might have made something of it, magnifying the whole thing until it became the nucleus of a first-class row, but he had more self-control. He was a scientist and he could afford to play the waiting game.

Of course, it would depend to some extent on how she reacted to his early arrival. Normally on these late nights, when the pressure of work at the laboratory demanded extra time, he would arrive home around ten o'clock, often finding her in bed and asleep (a gesture of defiance and protest), and a cold supper waiting for him on the kitchen table. Tonight, however, he had broken away from the unvarying schedule, deliberately, but not knowing why, and he had come home unexpectedly, ahead of time, in anticipation of what...?

For all his poise and self-confidence, it was a question he did not dare to answer.

As he finished the drink, he heard the bathroom door opening, and moved quietly into the hall. Lydia's slippered feet were almost noiseless on the landing carpet, but in a moment the sound of another door opening told him that she had gone into their bedroom. He decided to go up and talk to her. It would all be very good-humored. He would play with her, like a cat with a mouse, and all the time he would be talking to her with subtle calculated archness, probing her secrets without her knowledge. Then afterwards he would make love to her, fresh from the bath. He would show her that he was the master of the situation.

Feeling very much as though he were playing a cloak-and-dagger role he silently climbed the stairs. She was standing with her back to him as he entered the room, combing her hair in front of the long mirror of the dressing table. Under the powder-blue negligee she looked clean and cool, and in all she was every bit as beautiful and breathtaking as when he had first seen her, on the stage of that tiny theater in Northampton, playing a small part in a dramatic production by a struggling repertory company, now mercifully disbanded.

He couldn't even remember the name of the play--only Lydia, with her long corn-colored hair, her perfect oval face and peach-tinted complexion, and her clear blue eyes. Eyes that he sometimes thought were a little too wide open and doll-like. And here she was now, four and a half years later, only a few feet away from him yet in some indefinable way remote, as though in another dimension. Dimensional quadrature of the emotions, he thought ironically.

Strange how one could be cold and analytical in every phase of life and still be swept into unreasoning emotional unbalance by the sight of a beloved woman. Strange how your heart could pound at the awareness of her nearness. Strange to be in love and not understand why.