“One of us will have to watch all the time,” Greg told Russ. “We can’t take any chances. Stutsman will try to reach us sooner or later and we have to be ready for him.”

He glanced at the new radar screen they had set up that morning beside the bank of other controls. Any ship coming within a hundred miles of the laboratory would be detected instantly and pinpointed.

The board flashed now. In the screen they saw a huge passenger ship spearing down toward the airport south of them.

“With the port that close,” said Russ, “we’ll get a lot of signals.”

“I ordered the Belgium factory to rush work on the ship,” said Greg. “But it will be a couple of weeks yet. We just have to sit tight and wait. As soon as we have the ship we’ll start in on Chambers; but until we get the ship, we just have to dig in and stay on the defensive.”

He studied the scene in the screen. The ship had leveled off, was banking in to the port. His eyes turned away, took in the laboratory with its crowding mass of machinery.

“We don’t want to fool ourselves about Chambers,” he said. “He may not have the power here on Earth that he does on the other planets, but he’s got plenty. Feeling the way he does, he’ll try to finish us off in a hurry now.”

Russ reached out to the table that stood beside the bank of controls and picked up a small, complicated mechanism. Its face bore nine dials, with the needles on three of them apparently registering, the other six motionless.

“What is that?” asked Greg.

“A mechanical detective,” said Russ. “A sort of mechanical shadow. While you were busy with the stock market stunt, I made several of them. One for Wilson and another for Chambers and still another for Craven.” He hoisted and lowered the one in his hand. “This one is for Stutsman.”

“A shadow?” asked Greg. “Do you mean that thing will trail Stutsman?”

“Not only trail him,” said Russ. “It will find him, wherever he may be. Some object every person wears or carries is made of iron or some other magnetic metal. This ‘shadow’ contains a tiny bit of that ridiculous military decoration that Stutsman never allows far away from him. Find that decoration and you find Stutsman. In another one I have a chunk of Wilson’s belt buckle, that college buckle, you know, that he’s so proud of. Chambers has a ring made of a piece of meteoric iron and that’s the bait for another machine. Have a tiny piece off Craven’s spectacles in his machine. It was easy to get the stuff. The force field enables a man to reach out and take anything he wants to, from a massive machine to a microscopic bit of matter. It was a cinch to get the stuff I needed.”

Russ chuckled and put the machine back on the table. He gestured toward it.

“It maintains a tiny field similar to our television field,” he explained. “But it’s modified along a special derivation with a magnetic result. It can follow and find the original mass of any metallic substance it may contain.”

“Clever,” commented Greg.

Russ lit his pipe, puffed comfortably. “We needed something like that.”

The red light on the board snapped on and blinked. Russ reached out and slammed home the lever, twirled dials. It was only another passenger ship. They relaxed, but not too much.

“I wonder what he’s up to,” said Russ.

Stutsman’s car had stopped in the dock section of New York. Crumbling, rotting piers and old tumbledown warehouses, deserted and unused since the last ship sailed the ocean before giving way to air commerce, loomed darkly, like grim ghosts, in the darkness.

Stutsman had gotten out of the car and said: “Wait here.”

“Yes, sir,” said the voice of the driver.

Stutsman strode away, down a dark street. The televisor kept pace with him and on the screen he could be seen as a darker shape moving among the shadows of that old, almost forgotten section of the Solar System’s greatest city.

Another shadow detached itself from the darkness of the street, shuffled toward Stutsman.

“Sir,” said a whining voice, “I haven’t eaten ...”

There was a swift movement as Stutsman’s stick lashed out, a thud as it connected with the second shadow’s head. The shadow crumpled on the pavement. Stutsman strode on.

Greg sucked in his breath. “He isn’t very sociable tonight.”

Stutsman ducked into an alley where even deeper darkness lay. Russ, with a delicate adjustment, slid the televisor along, closer to Stutsman, determined not to lose sight of him for an instant.

The man suddenly turned into a doorway so black that nothing could be seen. Sounds of sharp, impatient rappings came out of the screen as Stutsman struck the door with his stick.

Brilliant illumination sprang out over the doorway, but Stutsman seemed not to see it, went on knocking. The colors on the screen were peculiarly distorted.

“Ultra-violet,” grunted Greg. “Whoever he’s calling on wants to have a good look before letting anybody in.”

The door creaked open and a shaft of normal light spewed out into the street, turning its murkiness to pallid yellow.

Stutsman stepped inside.

The man at the door jerked his head. “Back room,” he said.

The televisor slid through the door into the lighted room behind Stutsman. Dust lay thick on the woodwork and floors. Patches of plaster had broken away. Furrows zigzagged across the floor, marking the path of heavy boxes or furniture which had been pushed along in utter disdain of the flooring. Cheap wall-paper hung in tatters from the walls, streaked with water from some broken pipe.

But the back room was a startling contrast to the first. Rich, comfortable furniture filled it. The floor was covered with a steel-cloth rug and steel-cloth hangings, colorfully painted, hid the walls.

A man sat under a lamp, reading a newspaper. He rose to his feet, like the sudden uncoiling of springs.

Russ gasped. That face was one of the best known faces in the entire Solar System. A ratlike face, with cruel cunning printed on it that had been on front pages and TV screens often, but never for pay.

“Scorio!” whispered Russ.

Greg nodded and his lips were drawn tight.

“Stutsman,” said Scorio, surprised. “You’re the last person in the world I was expecting. Come in. Have a chair. Make yourself comfortable.”

Stutsman snorted. “This isn’t a social call.”

“I didn’t figure it was,” replied the gangster, “but sit down anyway.”

Gingerly Stutsman sat down on the edge of a chair, hunched forward. Scorio resumed his seat and waited.

“I have a job for you,” Stutsman announced bluntly.

“Fine. It isn’t often you have one for me. Three-four years ago, wasn’t it?”

“We may be watched,” warned Stutsman.

The mobster started from his chair, his eyes darting about the room.

Stutsman grunted disgustedly. “If we’re watched, there isn’t anything we can do about it.”

“We can’t, huh?” snarled the gangster. “Why not?”

“Because the watcher is on the West Coast. We can’t reach him. If he’s watching, he can see every move we make, hear every word we say.”

“Who is it?”

“Greg Manning or Russ Page,” said Stutsman. “You’ve heard of them?”

“Sure. I heard of them.”

“They have a new kind of television,” said Stutsman. “They can see and hear everything that’s happening on Earth, perhaps in all the Solar System. But I don’t think they’re watching us now. Craven has a machine that can detect their televisor. It registers certain field effects they use. They weren’t watching when I left Craven’s laboratory just a few minutes ago. They may have picked me up since, but I don’t think so.”

“So Craven has made a detector,” said Greg calmly. “He can tell when we’re watching now.”

“He’s a clever cuss,” agreed Russ.

“Take a look at that machine now,” urged Scorio. “See if they’re watching. You shouldn’t have come here. You should have let me know and I would have met you some place. I can’t have people knowing where my hideout is.”

“Quiet down,” snapped Stutsman. “I haven’t got the machine. It weighs half a ton.”

Scorio sank deeper into his chair, worried. “Do you want to take a chance and talk business?”

“Certainly. That’s why I’m here. This is the proposition. Manning and Page are working in a laboratory out on the West Coast, in the mountains. I’ll give you the exact location later. They have some papers we want. We wouldn’t mind if something happened to the laboratory. It might, for example blow up. But we want the papers first.”

Scorio said nothing. His face was quiet and cunning.

“Give me the papers,” said Stutsman, “and I’ll see that you get to any planet you want to. And I’ll give you two hundred thousand in Interplanetary Credit certificates. Give me proof that the laboratory blew up or melted down or something else happened to it and I’ll boost the figure to five hundred thousand.”

Scorio did not move a muscle as he asked: “Why don’t you have some of your own mob do this job?”

“Because I can’t be connected with it in any way,” said Stutsman. “If you slip up and something happens, I won’t be able to do a thing for you. That’s why the price is high.”

The gangster’s eyes slitted. “If the papers are worth that much to you, why wouldn’t they be worth as much to me?”

“They wouldn’t be worth a dime to you.”

“Why not?”

“Because you couldn’t read them,” said Stutsman.

“I can read,” retorted the gangster.

“Not the kind of language on those papers. There aren’t more than two dozen people in the Solar System who could read it, perhaps a dozen who could understand it, maybe half a dozen who could follow the directions in the papers.” He leaned forward and jabbed a forefinger at the gangster. “And there are only two people in the System who could write it.”

“What the hell kind of a language is it that only two dozen people could read?”

“It isn’t a language, really. It’s mathematics.”

“Oh, arithmetic.”

“No,” Stutsman said. “Mathematics. You see? You don’t even know the difference between the two, so what good would the papers do you?”

Scorio nodded. “Yeah, you’re right.”