"What was the snooping you said you had to do?" Griffin asked.

"Dates. Times. Briefly, I found that the run of accidents has been building up to a peak. At first, it was just small meters that went wrong. Then bigger, more complex stuff. And, finally, the Monster went. See the pattern?"

The other men nodded.

"You're the therapist," Griffin said. "What do you suggest?"

"Shock treatment," said David MacHeath.

Just how Dr. Konrad Bern got wind of the fact that a squad of FBI men had come to the project to arrest him that evening is something that MacHeath didn't know until later. He was busy at the time, ignoring anything but what he was interested in. It always fascinated him to watch the mind of a psychokinetic expert at work. He couldn't do the trick himself, and he was always amazed at the ability of anyone who could.

It was like watching a pianist play a particularly difficult concerto.

A person can watch a pianist, see every move he is making, and why he is making it. But being able to see what is going on doesn't mean that one can duplicate the action. MacHeath was in the same position.

Telepathically, he could observe the play of emotions that ran through a psychokinetic's mind--the combinations of avid desire and the utter loathing which, playing one against another, could move a brick, a book, or a Buick if the mind was powerful enough. But he couldn't do it himself, no matter how carefully he tried to follow the raging emotions that acted as two opposing jaws of a pair of tongs to lift and move the object.

And so engrossed was he with the process that he did not notice that Konrad Bern had eluded the FBI. He was unaware of what had happened until one of the Federal agents rapped loudly on the workshop door.

Almost instantly, MacHeath picked up the information from the agent's mind. He glanced at Griffin and Benbow. "You two can handle it. Be careful you don't overdo it."

Then he went to the door and opened it a trifle. "Yes?"

The man outside showed a gold badge. "Morgan, FBI. You David MacHeath?"

"Yes." MacHeath stepped outside and showed the FBI man his identification.

"We were told to co-operate with you in this Konrad Bern case. He's managed to slip away from us somehow, but we know he's still in the area. He can't get past the gate."

MacHeath let his mind expand until it meshed with that of Dr. Konrad Bern.

"There is a way out," MacHeath snapped. "The acceleration tube."

"What?"

"Come on!" He started sprinting toward the elevators. He explained to the FBI agent as they went.

"The acceleration tube of the ultracosmotron runs due north of here for two miles underground. The guard at the other end won't be expecting anyone to be coming from the inside of the target building.

If Bern plays his cards right, he can get away."

"Can't we phone the target building?" the FBI man asked.

"No. We shut off all the electrical equipment and took down some of the wires so we could balance the acceleration fields."

"Well, if he's on foot, we could send a car out there. We'd get there before he does. Uh ... wouldn't we?"

"Maybe. But he'll kill himself if he sees he's trapped." That wasn't quite true. Bern was ready to fight to the death, and he had a heavy pistol to back him up. MacHeath didn't want to see anyone killed, and he didn't want stray bullets flying around the inside of that tube or in the target room.

MacHeath and the FBI agent piled out of the elevator at the bottom of the shaft. Dr. Roger Kent was standing at the head of the stairs that spiraled down to the gun chamber. Dr. Kent knew that Bern had gone down the stairway, but he didn't know why.

"He's our saboteur," MacHeath said quickly. "I'm going after him. As soon as I close the door and seal it, you turn on the pumps. Lower the air pressure in the tube to a pound per square inch below atmospheric. That'll put a force of about a ton and a quarter against the doors, and he won't be able to open them."

Dr. Kent still didn't grasp the fact that Bern was a spy.

"Explain to him, Morgan," MacHeath told the Federal agent. He went on down the spiral staircase, knowing that Kent would understand and act in plenty of time.

The door to the tube was standing open. MacHeath slipped on a pair of the sponge-soled shoes, noticing angrily that Bern hadn't bothered to do so. He went into the tube and closed the door behind him. Then he started down the blackness of the tube at a fast trot. Ahead of him, in the utter darkness, he could hear the click of heels as the leather-shod Bern moved toward the target end of the long tube.

Neither of them had lights. They were unnecessary, for one thing, since there was only one direction to go and there were no obstacles in the path. Bern would probably have carried a flashlight if he'd been able to get his hands on one quickly, but he hadn't, so he went in darkness. MacHeath didn't want a light; in the darkness, he had the advantage of knowing where his opponent was.

Every so often, Bern would stop, listening for sounds of pursuit, since his own footsteps, echoing down the gla.s.s-lined cylinder, drowned out any noise from behind. But MacHeath, running silently on the toes of his thick-soled shoes, kept in motion, gaining on the fleeing spy.

A two-mile run is a good stretch of exercise for anyone, but MacHeath didn't dare slow down. As it was, Konrad Bern was already tugging frantically at the door that led to the target room by the time MacHeath reached him. But the faint sighing of the pumps had already told MacHeath that the air pressure had been dropped. Bern couldn't possibly get the door open.

MacHeath's lungs wanted to be filled with air; his chest wanted to heave; he wanted to pant, taking in great gulps of life-giving oxygen.

But he didn't dare. He didn't want Bern to know he was there, so he strained to keep his breath silent.

He stepped up behind the physicist in the pitch blackness, and judging carefully, brought his fist down on the nape of the man's neck in a hard rabbit punch.

Konrad Bern dropped unconscious to the floor of the tube.

Then MacHeath let his chest pump air into his lungs in long, harsh gasps. Shakily, he lowered himself to the floor beside Bern and squatted on his haunches, waiting for the hiss of the bleeder valve that would tell him that the air pressure had been raised to allow someone to enter the air lock.

It was Morgan, the FBI man, who finally cracked the door. Griffin and Dr. Kent were with him.

"You all right?" asked Morgan.

"I'm fine," MacHeath said, "but Bern is going to have a sore neck for a while. I didn't hit him hard enough to break it, but he'll get plenty of sleep before he wakes up."

More FBI men came in, and they dragged out the unprotesting Bern.

Dr. Kent said: "Well, I'm glad that's over. I'll have to get back and see what Dr. Nordred is raving about."

"Raving?" asked MacHeath innocently.

"Yes. While I was in the pump room reducing the pressure, he called me on the interphone. Said he'd been looking all over for me. He and Luvochek and Bessermann are up in the lab." He frowned. "They claim that one of the radiolead samples was floating in the air in the lab.

It's settled down now, I gather, but it only weighs a fraction of what it should, though it's gaining all the time. And that's ridiculous.

It's not at all what Dr. Nordred's theory predicted." Then he clamped his lips together, thinking perhaps he had talked too much.

"Interesting," said MacHeath blandly. "Very interesting."

Senator Gonzales sat in Brian Taggert's sixth-floor office in the S.M.M.R. building and looked puzzled. "All right, I grant you that Bern couldn't have been the saboteur. Then why arrest him?"

Dave MacHeath took a drag from his cigarette before he answered. "We had to have a patsy--someone to put the blame on. No one really believed that it was just bad luck, but they'll all accept the idea that Bern was a saboteur."