No light shone in the chambers of the computer complex. The electronic monitors that kept watch didn't need any light, and no people were here tonight. There might be one or two night owls still working in the laboratories along the main corridor, but Katerina Shumilova hadn't seen any. Hopefully they hadn't seen her either, but even if they had, why should they be concerned? She was a computer technician, with every right and privilege to come and go in the computer complex when she pleased.

She was also a crack agent for the KGB, the Soviet secret police. Her presence here as a full-fledged member of the complex's staff was a major breakthrough for Soviet intelligence. She had been here three months. Tonight she was to bring off the first full-fledged act of sabotage against the «Project.»

It would not destroy or disable anything that could not be repaired or replaced fairly quickly. Doing that would risk exposing herself to British counterintelligence, throwing away all the time and effort involved in placing her here. The KGB preferred not to waste important and well-placed agents to win small victories.

No, what she would do tonight would simply cause temporary but spectacular and annoying damage. She would see what the other people on the Project did to repair that damage. She would listen very carefully to what they said. Everything she saw and heard would tell her more about the nature of the computers involved in the Project, and therefore more about the Project itself.

For all the time she had spent in the complex, she still knew practically nothing about the ultimate purpose of the Project. She knew a good deal, but all of it was fairly obvious.

The Project was vital to British security. She knew that simply from the size of the complex and the expense involved in building and equipping it. With British capitalism in its final agonies, the British would never pour tens of millions of pounds into something that wasn't expected to produce enormous returns.

The Project itself involved some major scientific breakthrough, and that breakthrough involved advanced computers. She knew that from even a casual look around the complex, and also from the fact that Lord Leighton appeared to be heavily involved in the Project. Leighton's reputation as a brilliant, innovative scientist, an absolute wizard with computers, was worldwide.

British intelligence was taking a hand in the Project. She knew that, or at least suspected it. She had seen the man known as J in the complex too often for there to be any other explanation. That was neither surprising nor mysterious. If the Project was as important as it seemed, of course British intelligence would be concerned with it. They would be fools not to be, and Katerina did not think British intelligence was foolish. Those Soviet agents who thought otherwise very seldom lived long enough to learn from their mistakes.

There was one unanswered question she'd found worth thinking about. What was Richard Blade's connection with the Project? It was an important one, considering how often he was mentioned in even the few documents she'd been able to examine. She'd also seen him in the complex twice. None of this told her very much.

She was familiar with the KGB's dossiers on Blade and on other top ranked British intelligence operatives. What she knew of Blade only deepened the mystery. He was a field man, a superb and formidable one with an almost legendary reputation. He was about the last man in British intelligence who would be assigned to any sort of desk job in connection with a research project.

She realized that it was time she stopped running her mind over ground she'd already covered many times. Somebody might still come in, and then there would certainly be delay, perhaps awkward questions. Ten years of training and field work had hammered a number of rules into her. One of them was: don't waste opportunities.

She unbuttoned the top two buttons of her laboratory coat and reached into the concealed pocket sewn into it just under her left breast. She drew out the doctored tape, checked the serial number, and double-checked the setting on the anti-tamper charge. Then she reached down and opened the lid of the main tape storage bin. She'd seen Lord Leighton do it a number of times, and her memory was superb. She could match every one of his motions as precisely as a ballet dancer.

The tapes already on the racks inside the bin gleamed faintly in the dim glow from the small light set in the lid. There was a space near the end of the second row from the top. Katerina took a firm grip on her tape and reached down toward the empty space.

If the computer rooms hadn't been soundproofed, her scream would have been heard all over the complex. The soft thud as she fell unconscious to the floor wouldn't have been heard more than a few feet away.

The signal did not awaken Lord Leighton, since he wasn't asleep. He was seated at the desk in the small room where he lived while Blade was in Dimension X. Being awake at three o'clock in the morning was nothing unusual for him. He seldom slept more than four hours a night. When a man is past eighty, he knows that he has only so many days' work left. Every hour spent sleeping is one that can't be put to some better use.

Then the desk lamp started flashing. Three shorts and a long, three shorts and a long, three shorts and a long-the letter V, over and over again. The lamp was hooked into the anti-sabotage devices built into several of the key elements of the computer system. Each element had its own code letter. The letter V meant the main tape file.

Leighton grinned. There was real pleasure in seeing his own work justifying itself. He had installed and wired in every one of those anti-sabotage devices with his own hands, working late at night and saying nothing to anybody. That was one certain way of keeping a secret-make sure it would die with you.

It occurred to Leighton that few people might have suspected in any case. Few people realized how well he could still handle a spot welder or a circuit diagram. Of course, they didn't realize just how long he'd been at work, and what that meant.

Sixty years ago there had been fewer high-priced technicians around, and many more chances of electrocuting yourself in the average laboratory. He was one of the last survivors of that generation of scientists. He hadn't forgotten all the things he'd had to learn in order to do his early work.

He stood up, flicked off the light, and pulled on his coat. He had better go see what had happened. Then as an afterthought he reached into his desk drawer and pulled out the huge Webley revolver J had given him for a birthday present last year. Frankly, he thought it was rather, primitive. He would have preferred a hand laser, and he hoped to live long enough to see them available. But he couldn't turn down a present from J, or neglect to keep it in working condition. Besides, the anti-sabotage devices might have really caught a saboteur, instead of having some sort of electronic fit. If that was the case, the gun might come in handy.

The device had been telling the truth. Lord Leighton realized that the moment he saw the white-coated figure sprawled facedown on the floor by the tape bin. He wasn't going to need the gun, though.

He knelt down, made sure the woman was still breathing normally, then opened the door to the main computer room, his own inner sanctum. Gritting his teeth at the pain in his back, he hauled the woman through the door. He kept on hauling until he reached the changing booth, then shoved the woman inside. She would not be very comfortable, but once he locked the door she could see and hear nothing. As for getting out, that would take a stick of dynamite.

Then Leighton pulled the observer seat down and collapsed on it for a moment. He hadn't exerted himself like that in months. Unfortunately, this was just the beginning of what looked like a long, tiring night.