A gray mist swallowed the downhill path less than a hundred yards ahead. The big man still came down the path at a steady lope. His eyes were fixed on the mist ahead, but his long legs never broke their rhythm and his feet in their scarred hiking boots always struck firm ground. He carried a heavy pack on his back and a long staff in one hand, while ragged hair and beard suggested that he'd been on the move for days if not weeks.

Richard Blade had indeed been moving across the Highlands of Scotland for fourteen days, living rough, traveling far, sleeping little and eating less, getting steadily more tired but also steadily happier. Now he was covering the last few miles as fast as his legs would carry him. Physically he was weary, but within he felt stronger and readier to face this world or any other world than he'd felt for months.

Richard Blade was a man who had to face many worlds. He was the only man on earth who could travel into other Dimensions and remain alive and sane. Even for him it wasn't easy. If Blade hadn't been a nearly perfect combination of mental and physical qualities, he would have long since lain in a grave in some other Dimension far away across infinity.

In fact, if Blade hadn't been that nearly perfect combination, no one would ever have known of those distant Dimensions. Lord Leighton, Britain's most original and creative scientific mind, conceived the experiment of linking a computer and a human brain, to form an instant genius. The human brain he chose was Richard Blade's.

Then came the accident. Instead of becoming the intended superbrain, Richard Blade vanished entirely from Britain. He appeared in a strange, violent, and primitive land where he had to use all his strength and wits to survive. Somehow he succeeded, and in time Lord Leighton managed to reverse the workings of the computer and bring him back to Britain.

It was an accident, but it was one that could be repeated over and over. It could be repeated as long as there was someone able to travel into what they called Dimension X and return alive and sane. So far that meant Richard Blade, and no other living human being.

Project Dimension X was balanced precariously on the life of one man. Such a vulnerable project would normally have never been allowed to grow to anything like the size of Project Dimension X. In Britain research money did not grow on bushes-as Lord Leighton had to be reminded frequently.

There was nothing normal about Project Dimension X, however. Carried far enough, it just might give Britain the ability to draw on the resources of Dimension X at will. Would the end of this be a new British Empire, stretching across infinity instead of across the earth? It could be. Certainly it was a magnificent dream.

So Project Dimension X would go on, whether it had one man or a hundred ready to send out. Meanwhile, the secret of the discovery would be kept, at whatever cost in lies, money, or human lives. It was easy to imagine what Britain's enemies might do with the secret of Dimension X. It was almost as easy to imagine how some of Britain's friends might suddenly become enemies if the secret got out.

Project Dimension X would go on its way, and Richard Blade would go out time after time, to face one new and nightmarish world after another. He'd gone out twenty-four times, he'd faced twenty-four strange worlds, he'd returned to Britain twenty-four times.

Over the past two months he'd begun to wonder if he could do it again.

Richard Blade had always survived his adventures in Dimension X. Some of the people who'd been caught up in those adventures hadn't been so lucky. There were two in particular who preyed heavily on Blade's mind.

One was Katerina Shumilova, a Russian secret agent who'd made an involuntary trip into Dimension X after being detected trying to sabotage the Project. Lord Leighton decided that making her disappear into Dimension X was the best way of preserving the vital secret.

She survived her original trip into the hands of the savage Ganthi and a meeting with Blade. She even survived a second trip across the Dimensions, to the black jade city of Kano. By that time there was love between her and Blade, and both of them knew it.

Then in the battle to save Kano from the Raufi of the great desert, she died. A little of Blade died with her. She was a woman with all of his own strengths, and that made it seem unimportant that she'd begun as an enemy.

The other woman was named Galina Haran. She came from a Russia that was not Russia, a place called Russland in a monstrously strange Dimension where things were almost as they were in Home Dimension, but not quite. The Red Flames of Russland fought against the Empire of Englor. From Galina Haran's discoveries in genetics and cloning, they bred flying dragons to swoop down on Englor. In the end Blade led airborne commandos to destroy the dragons in their nest, deep inside Russland. Then the computer drew him home to Britain and Galina came with him, carrying all the notes on her discoveries as well.

That should have been a triumph, for Britain's biological sciences, for Project Dimension X, for Richard Blade. Perhaps it would be, in time. Meanwhile, the passage across the Dimensions left Galina with no more mind than a six-month old baby. Her brain was physically intact, so in theory the damage should not be permanent. But none of the doctors who'd examined Galina had much hope for her recovery. Galina Haran would spend years and perhaps the rest of her life as a helpless idiot. Blade couldn't escape the feeling that this was his fault.

Blade told himself that he had to go on doing his duty to Britain, at any cost to himself or to other people. Every other possible duty to himself or to anyone else had to take a back seat.

He told himself this every waking minute of the day, and in the daylight it seemed that he made sense. It was different by night. In the darkness Katerina came to him, her face twisted with her final agony, and also Galina, her face blank and drooling. They came so often and so vividly that he began to feel haunted.

He knew he had to get rid of this feeling, or it would sooner or later end his life and therefore Project Dimension X. Nightmares never killed a man outright. They would eventually slow a man's physical and mental reflexes. He would go off into Dimension X- in that condition, and from that journey he would not return.

Perhaps he could have driven away the nightmares with liquor or women. Too much liquor took the edge off mind and body as surely as any nightmares. As for the women, Blade could not use other people simply as weapons to fight his own nightmares. He would have to fight and win this battle alone.

So he pulled on his oldest clothes, slung a pack on his back, and walked off into the Highlands of Scotland.

Now it was fourteen days later, and he was walking out again. He was walking out with his pack nearly empty, his boot soles worn thin, bruises or blisters or a coat of dirt on every part of his body, and peace of mind for the first time in months. The two weeks in the Highlands had done the job he'd hoped they would do-two weeks of being alone, two weeks of walking himself into a healthy exhaustion every day and sleeping a dreamless sleep every night. He could look himself in the face now, without wondering if he was looking at a murderer. Once more he could face the world and his next trip into Dimension X.

Blade had chosen a part of the Highlands where human dwellings were rare and telephones were rarer. So it took several hours' more stiff hiking before he was on to a decent road. He had two more hours of traveling along the road, with the light fading and the mist thickening around him. At the end of it all lay a country hotel, where the owner and his wife waited for Blade with a hot bath, clean clothes, good whiskey, a meal large enough for two ordinary men, and finally a telephone connection to London.