hardly had to strain itself to drive the automobile at top speed, and, as long as there was traction, no grade could stall the car. Theoretically, it could climb straight up a wall.

Not that Sam Bending had any intention of climbing a wall with it.

He even had power left over for the sound-effects gadget and the air-heater that made the thing appear to be powered by an ordinary turbo-electric engine. He listened and smiled as the motors made satisfying sounds while he pulled out of the parking lot and into the street. He kept that pleased, self-satisfied grin on his face for six blocks.

And then he began to notice that someone was following him.

At first, he hadn't paid much attention to it. The car was just a common Ford Cruiser of the nondescript steel blue color that was so popular. But Bending had been conscious of its presence for several blocks. He looked carefully in the mirror.

Maybe he was wrong. Maybe it had been several cars of that same color that had moved in and out of the traffic behind him. Well, he'd soon see.

He kept on going toward the North-South Expressway, and kept watching the steel-blue Ford, glancing at his rear view mirror every time he could afford to take his eyes off the traffic.

It moved back and forth, but it was never more than three cars behind him, and usually only one. Coincidence? Possibly.

At Humber Avenue, he turned left and drove southwards. The steel-blue Ford turned, too. Coincidence? Still possible.

He kept on going down Humber Avenue for ten blocks, until he came to the next cross street that would take him to a lower entrance to the North-South Expressway. He turned right, and the Ford followed.

At the ramp leading to the northbound side of the Expressway, the Ford was two cars behind.

Coincidence? No. That's pushing coincidence too far. If the men in the car had actually intended to go north on the Expressway, they would have gone on in the direction they had been taking when Bending first noticed them; they wouldn't have gone ten blocks south out of their way.

Bending's smile became grim. He had never liked the idea of being followed around, and, since the loss of one of his Converters, he was even touchier about the notion. Trouble was, his fancy, souped-up Lincoln was of no use to him at all. He could outrun them on a clear highway—but not on the crowded Expressway. Or, conversely, he could just keep on driving until they were forced to stop for fuel—but that could be a long and tedious trip if they had a full tank. And besides, they might make other arrangements before they went dry.

Well, there was another way.

He stayed on the Expressway for the next twenty miles, going far north of where he had intended to turn off. At the Marysville Exit, he went down the ramp. He had been waiting for a moment when the Ford would be a little farther behind than normal, but it hadn't come; at each exit, the driver of the trailing car would edge up, although he allowed himself to drop behind between exits. Whoever was driving the car knew what he was doing.

At the bottom of the ramp, Bending made a left turn and took the road into Marysville. It was a small town, not more than five or six thousand population, but it was big enough.

There weren't many cars on the streets that led off the main highway. Bending made a right turn and went down one of the quiet boulevards in the residential section. The steel-blue Ford dropped behind as they turned; they didn't want to make Bending suspicious, evidently.

He came to a quiet street parallel to the highway and made a left turn. As soon as he was out of sight of his pursuers, he shoved down on the accelerator. The car jumped ahead, slamming Bending back in his seat. At the next corner, he turned left again. A glance in the mirror showed him that the Ford was just turning the previous corner.

Bending's heavy Lincoln swung around the corner at high speed and shot back toward the highway. At the next corner, he cut left once more, and the mirror showed that the Ford hadn't made it in time to see him turn.

They'd probably guess he'd gone left, so he made a right turn as soon as he hit the next street, and then made another left, then another right. Then he kept on going until he got to the highway.

A left turn put him back on the highway, headed toward the Expressway. The steel-blue car was nowhere in sight.

Bending sighed and headed back south towards home.

Sam Bending knew there was something wrong when he pulled up in front of his garage and pressed the button on the dashboard that was supposed to open the garage door. Nothing happened.

He climbed out of the car, went over to the door of the garage, and pushed the emergency button. The door remained obstinately shut.

Without stopping to wonder what had happened, he sprinted around to the front door of the house, unlocked it, and pressed the wall switch. The lights didn't come on, and he knew what had happened.

Trailing a stream of blue invective, he ran to the rear of the house and went down the basement stairs. Sure enough. Somebody had taken his house Converter, too.

And they hadn't even had the courtesy to shunt him back onto the power lines.

At his home, he had built more carefully than he had at the lab. He had rigged in a switch which would allow him to use either the Converter or the regular power sources, so that he could work on the Converter if he wanted to. His basement was almost a duplicate of his lab in the city, except that at home he built gadgets just for the fun of watching them work, while at the lab he was doing more serious research.

He went over to the cabinet where the switch was, opened it, and punched the relay button. The lights came on.

He stalked back up the stairs and headed for the visiphone. First, he dialed his patent attorney's office; he needed some advice. If Power Utilities had their hands on two out of three of his Converters, there might be some trouble over getting the patents through.

The attorney's secretary said he wasn't in, and she didn't know if he expected to be back that day. It was, she informed Bending rather archly, nearly five in the afternoon. Bending thanked her and hung up.

He dialed the man's home, but he wasn't there, either.

Sam Bending stuck a cigarette in his mouth, fired it up, walked over to his easy-chair and sat down to think.

According to the police, the first Converter had been stolen on Friday night. The second one had obviously been taken sometime this morning, while he was in the lab with the police.

That made sense. The first one they'd tried to open had fused, so they decided to try to get a second one. Only how had they known he had had more than one? He hadn't told anyone that he had three—or even two.

Well, no matter. They had found out. The question was, what did he do next? Inform the police of the two thefts or—

There was a car pulling up outside the house.

Sam stood up and glanced out the window. It was a steel-blue Ford.

By Heaven! Did they intend to steal the third Converter, too? And right in front of his eyes, before it even got decently dark?

Sam was so furious that he couldn't even think straight. When the two men climbed out of the car and started walking toward the house, Sam ran back into his study, pulled open his desk drawer, and took out the .38 Special he kept there. It was the work of seconds to thumb six cartridges into the chambers and swing the cylinder shut.

The door chime sounded.

Sam went back into the front room with the revolver in his jacket pocket and his hand ready to fire it.

"Who is it?" he called, in what he hoped was a steady voice.

"We're Special Agents of the FBI," said a voice. "May we see you for a few moments, Mr. Bending?"

"Certainly. Come on in; the door's unlocked." Just walk in, you phonies! Just trot right on in, he thought.

And they