The ringing of the telephone broke Richard Blade's sleep. As always, he was awake in an instant. In his profession those who were slow to awake didn't last long. He reached one long tanned arm out of bed and picked up the receiver.

«Hello, Crawford here.» That was his cover name when traveling abroad on personal business. He was no longer an active field agent for the secret intelligence agency MI6. But here certainly must be people who remembered that a «Richard Blade» had been one of MI6's top agents for nearly twenty years. In those years he had done a good deal to give many people scores and grudges against him. If his name showed up nakedly on a Riviera hotel register, some of those people might be tempted to try settling those scores. And Blade preferred to take his holidays without interruptions or excitement. He got more than enough excitement on his new job.

«Ah, Francis,» came the familiar paternal voice on the other end of the line. Fuzzed and distorted as it was by the long-distance line from London, J's voice was unmistakable. The old spymaster had been Blade's chief in MI6, and was in an odd sort of way still his chief. «How are you? Riviera agreeing with you?»

«Very much, sir.»

«Have anything doing that you can't break off?»

«Nothing in particular, sir.» That was approximately true. There had been an American girl, on her way to Oxford. But she couldn't be called particular. Decidedly not. There was an impressive number of hours in that young lady's bedroom log, Blade was sure. «Has business suddenly picked up?»

«Not worth mentioning. But his lordship wants to call a conference on the twelfth to discuss one of the new lines. Number Nineteen, I think he said.»

«Very good, sir. I'll be there in plenty of time.»

The line went dead. Blade put the receiver back in place and lay back in the bed. Like his identity, his profession was concealed while he was abroad behind a cover story and a code. But there were reasons for concealing his profession that went beyond his personal safety.

There was no single word to describe Blade's profession, a profession unknown to the public-or so he and J both devoutly hoped. And Blade doubted if there ever would be a word. How can you describe a man whose job it is to travel into alternate dimensions-not quite on alternate Thursdays, but much the same way a deep-sea sailor goes on a long voyage? Blade didn't know. All he knew was that he was the best man in the world today for that job. And he enjoyed it. He had an adventurous temperament, but he had managed to be born in a century when there were few professions that offered that much chance for adventurers. He knew that he was very lucky.

His luck had begun the day that England's most brilliant and eccentric scientist, Lord Leighton, had decided to make an experiment. The experiment consisted of linking a man's brain directly into an advanced computer-or at least what had been an advanced computer then. Compared to what Lord Leighton used now, that first computer was hardly more than a child's toy. Leighton's goal was to radically increase the powers of both the human and the electronic intelligences, each taking strength from the other.

A good idea. Blade rather hoped that one day the original experiment could be carried out successfully. But things had not turned out as the scientist planned. Blade had awakened in a strange, barbaric world in which savage tribes and the votaries of even more savage religions roamed about and warred on one another. Thanks to his training, his muscles, his quick reflexes, and his quicker wits, he had survived and somehow been snatched back to Lord Leighton's laboratory.

Immediately Lord Leighton's original project went aglimmering for here was something ten times as important. The existence of alternate dimensions-Dimension X-had frequently been theorized. Now it had been proved. And now it seemed possible to travel at will into those dimensions, explore them, discover their resources of knowledge and raw materials, bring wealth back to England. It was a discovery of enormous national importance.

So Project Dimension X was born. Lord Leighton's fertile brain created successively more sophisticated computers. The prime minister's authority and political skills produced money and turned aside awkward questions-at least so far. J traveled about on a hundred odd items of needed business. And Blade himself went into Dimension X-twelve times now-explored, wandered about, and helped the people he found there. All twelve times he had arrived in Dimension X naked as the day he was born, and all twelve times he had survived and even flourished by his trained mind and athlete's body.

But perhaps this time would be different. «Number Nineteen» was the code for one of the innumerable subprojects the whole Dimension X business had spawned. Blade had become wearier and wearier of having to contrive even the most basic clothes and weapons when he arrived in a new dimension. After his return from his last trip, he had taken the matter up with Lord Leighton. He had pointed out, among other things, that he was relying too much on luck to keep sending him into these violent worlds stark naked. It was time to start seeing about sending a survival kit through the computer with him. J, who loved Blade like a son, had supported him.

Lord Leighton was used to having his weakness for subprojects criticized. He ignored these criticisms, of course, and plowed ahead. But now both Blade and J were actually urging him to go off on a new tangent. It was commonly believed that the scientist had a smaller version of one of his own computers in place of a heart, but Blade knew this wasn't quite correct. Still, Leighton must have been gratified, because he had gone straight to work on developing the survival kit. And he must have worked like a beaver, if the survival kit was ready so quickly. It had been barely a month since Blade returned from his last Dimension X trip to the warrior people of Zunga.

After breakfast the next morning, Blade checked out of the hotel and drove his rented Renault back into Cannes. There was a flight leaving for Paris at 10:15, and with a good deal of scurrying he just caught it. From Paris, another flight took him on to London. The airport bus trundled him into the city through a dreary late autumn afternoon, gray skies hanging low and threatening rain, fog, or a combination of the two. It was a relief to finally reach his own apartment, unpack his bags, and improvise a dinner.

Then there was a note for his charlady. She would probably wonder why he was dashing off again just after getting back from southern France. But she would wonder privately and quietly. She was not bound by the Official Secrets Act, of course, but MI6 had done a quick and quiet check on her before they let him hire her. The report had come back: the perfectly respectable widow of a sergeant in the Coldstream Guards, anything but a gossip.

There were times when Blade could work up a mood of blazing resentment against all the secrecy that surrounded his life. The Official Secrets Act had smashed his engagement, would probably keep him a bachelor until he retired, and had elbowed its way into his life in all sorts of little ways.

Eventually he went to bed because he couldn't think of anything better to do. When there was another trip into Dimension X coming up, he found it hard to concentrate on anything else. Home Dimension, his apartment with its books and bottles, even the women who shared his bed for a night or a week, all came to seem insubstantial and fleeting.

The heart of Project Dimension X was Lord Leighton's underground complex, two hundred feet below the Tower of London. It included offices, laboratories, a small but well-equipped hospital where Blade was examined and interviewed after each return, and the gigantic computer itself. Guarded on the surface by a squad of Special Branch men and down below by the latest electronic gear, the complex represented an investment approaching ten million pounds.