MacPherson shuffled the cards over and over again. His hands were almost steady.

“Want to place a limit on the bets?” he asked.

His two colleagues who had made the night drive with him from the University said nothing, but Rothman laughed.

“Today?” he said. “Today, the sky’s the limit.”

MacPherson rested the deck on the table and watched as Rothman stood up to look through the barred window at the glittering Arizona desert. Rothman had got thinner during his months of confinement; his shoulders were bony beneath the gray hospital robe and his balding head looked like a skull.

“Are you going to play?” asked MacPherson. “Or is poker too childish an amusement for a mathematician?”

Rothman turned his back to the window. “Oh, I’ll play. When three old friends from the Project suddenly turn up for a visit, even a madman will string along.”

Shuffling the cards again, MacPherson wished the other men would say something; it wasn’t fair of them to make him carry the conversation. Professor Avery, who had cut his physics classes in order to join the morning’s party, sat in glum silence. His plump face was pale, and behind thick-lensed spectacles which enlarged his eyes grotesquely, he blinked as he watched the flickering cards. Dr. Neill, from Physical Chemistry, was tapping his toe against the table leg, watching Rothman, who stood at the window, waiting.

“But we can’t have much of a game with only four people,” said Rothman. “We ought to have a fifth.”

“Maybe we can find someone.” MacPherson walked to the locked steel door and rattled the rectangular lattice set in at shoulder height, put his mouth to the metal bars and called out.

“Hey, Joe!”

An attendant in white uniform shuffled into the corridor of closed doors, carrying a tray with one hand and scratching his head with the other.

“How about joining us for a game of poker?”

Joe shook his head and grinned. “Not me, Professor! I start buddying around with the loonies, I lose my job.”

“But we’re not inmates!”

“Maybe not, but Dr. Rothman is.”

“Doesn’t prove I’m crazy, Joe,” said Rothman. “Conversely, not being inmates doesn’t prove these men are sane.”

“It’s a fact you don’t look any crazier to me than a lot of professors,” confessed Joe. “I don’t know. All I know is, I’m not crazy enough to break the rules and lose my job. Besides, you long-hairs wouldn’t stand a chance at poker with me.”

Still grinning, he shuffled out of sight down the hall.

MacPherson sighed and went back to the table. “Well, we’ll have to get along with just the four of us.”

“There’s always the unseen guest,” said Rothman, “but you won’t need to deal him a hand. He already holds all the cards.”

Neill looked up. “Stop hamming and sit down. Quit making like a maniac. It’s not even a good act.”

“Okay.” Rothman drew up a chair. “Now what was said about limiting the bets?”

“Why bother setting a limit?” said Neill. “We’re not likely to mistake each other for millionaires and we all got exactly the same pay when we were on the Project. Unless your sick pay has had two or three zeros tacked onto it, you’re not going to be making any wild bets, and as for the rest of us--”

“University professors are still being paid less than nightclub dancers,” said Avery. “You’re lucky to be out of the rat race, Rothman. While we worry about how to pay the grocery bill, you can relax, eating and sleeping at government expense. You never had it so good.”

“Maybe you’d like to get yourselves committed and keep me company?”

MacPherson rapped the deck on the table. “Stop that kind of talk. We came here to play poker.”

“Did you?” asked Rothman, grinning. “Then why don’t you deal?”

“Cut, Neill?” said MacPherson. As he shot the slippery cards over the table top, each flick of his thumb watched by Rothman’s intent eyes, he regretted this impulsive visit; it now seemed a gesture without meaning. He wondered whether the others were as nervous as he was.

On the drive over from Los Angeles during the night, Neill had seemed calm enough and even Avery, who had changed a lot during work on the Project, had chatted with them unconstrainedly. It was hard to be certain what other men were feeling, even when you had known them a long time, but it could not be pleasant for any of them to be visiting a former colleague who had been removed from the Project directly to a sanitarium.

“Tell me something,” said Rothman as he picked up his cards. “Do you still think I’m crazy?”

“Don’t be an idiot,” MacPherson snapped. “Do you think we’d cut our classes and drive nearly five hundred miles just to play poker with a lunatic?”

“No,” said Rothman. “That’s how I know. But why aren’t you frank about it? Why keep on pretending there wasn’t a special reason for your visit?”

Neill was beating his foot against the table leg again and Avery’s eyes were hard and staring as he examined his cards.

“Who’ll open?” MacPherson asked. “I can’t.”

“I can,” said Rothman. “I’m betting one blue chip. Listen, Avery, why won’t you look at me? If you think I’m hamming, what do you call your own act? How long are we going to go on kidding each other? They’ve shut me up here, but that doesn’t mean they’ve stopped me from logical thinking. My three old friends from the Project don’t turn up in the middle of a Friday morning just to calm my fevered brain with a card game.”

“What’s wrong with poker?” demanded MacPherson.

“Poker? Nothing. I know--It must be the test. Total conversion of matter to energy. Not just a minute percentage any more--total conversion. They’ve finished the set, haven’t they? They’re ready to test. They’re going to disintegrate Waaku, aren’t they? It must be today. Then this is the day the world ends. Tell me, when is zero hour?”

Neill’s cards had slipped from his fingers and he stooped to the floor, fumbling for them. Avery was bending one corner of a card, creasing it, smoothing it out, and creasing it again. Nobody was going to answer, MacPherson realized. They were leaving it up to him.

He spoke sharply. “You’re getting onto forbidden ground, Rothman. You know we’re not allowed to discuss the Project with you. We’re allowed to visit you only under the strictest promise not to speak of it at all. You’re certainly rational enough to understand what the therapists have told you, that you’d get well easily enough if you’d stop worrying. Forget about zero hour. Everything’s going to be all right.”

Rothman turned to look out the window. “Is it today?”

“How should we know? We’re only innocent bystanders now, like you. Remember, we all left the Project over six months ago, except Avery, and last month they let him go.”

Neill had rearranged his cards now and he looked at them instead of Rothman as he spoke. “There’s nothing to worry about. Your calculations were wrong. The test is not going to get out of control--if and when they make it. But they don’t tell us things any more.”

“Since they fired you,” said Rothman.

“That’s right, since they fired us,” Neill said. The creased corner of a card suddenly broke off in his fingers.

“If you didn’t believe in my calculations, why did you back me up? I didn’t ask you to. If you didn’t believe in the danger, why didn’t you stay out of the argument and keep your jobs? It wasn’t your fight. You could have kept out of it--or attacked me, like Avery.”

“All we did was insist that even if you had made a mistake in your calculations, that didn’t necessarily prove you were crazy,” said Neill. “We didn’t know whether you were right or not. We couldn’t argue about the math. Avery tore that to pieces and the boys at Columbia and Harvard backed him up. MacPherson and I aren’t competent to check your math. To us, you didn’t seem any crazier than the people who sent you here. But after you’d scared them silly, they had to do something to stop your scaring other people.”

He turned to pick up his cards again, but stopped at the sight of Avery. Avery was standing and crumpling a card spasmodically, his lips were moving without sound, and he was breathing rapidly.

“Look here,” said MacPherson. “You’d better change the subject. If little Joe passes by the door and hears us talking about the Project, he’ll have our visiting privileges revoked before you can say nuclear fission, and they’ll stay revoked forever.”

“How long is forever?” asked Rothman.

Avery threw down his cards and walked to the window. Through the bars, there was nothing to be seen but the expanse of sand, glinting in the morning sun, and a cactus plant casting a stubby shadow. He whirled to face the others.

“Look, MacPherson,” he burst out. “I’m fed up with this game. Snookums Rothman mustn’t think about the Project any more, so we mustn’t say the naughty word. But we were all in it together at the beginning and there was a while when we were all every bit as scared as he was. Why not tell him we came this morning in case--just in case--he’d heard about the test and was worrying? What’s the harm in telling him what the whole university knows? That zero hour is today, this morning, now!”

“Shut up, you fool!” said MacPherson.

But Rothman glanced at his cards again, then looked up. “When does it begin? What time is it now?”

“Don’t answer!” shouted MacPherson. “Are you trying to knock him off balance again?”

“I will answer!” said Avery. “I’m going to tell him. He scared us silly with his calculations; now let us scare him with some cold facts. It’ll do him good. Maybe when the test is over, if he finds--I mean when he finds--he was wrong, he’ll be cured.”

“Yes, and maybe he’ll really be crazy.”

Grabbing Avery fiercely by the arm, MacPherson tried to drag him to the door, but Avery broke away.

“Listen, Rothman!” Avery’s breath was coming quick and shallow. “Today is the day! Zero hour is eleven o’clock this morning!”

MacPherson sagged. No one spoke or moved as they all watched Rothman.

At last Rothman sighed, once. “What time is it now?”

From the door came a scratching sound. MacPherson turned to see Joe, grinning at them through the steel lattice.

“How’s things?” Joe wanted to know. “Thought I heard a commotion in here. Doc Rothman’s not acting up, I hope?”

“Everything’s under control, Joe,” MacPherson assured him. “Just having a friendly game.”

“Don’t cheat while they’re watching you,” said Joe, and his face disappeared.

“Well, the murder’s out,” said MacPherson.

“No use kidding you any longer,” Neill said, fanning his cards. “Eleven o’clock this morning. Six o’clock tomorrow morning, Waaku time. But it’s just another test. Nothing’s going to happen.”

Avery took off his glasses and began to polish the lenses. “Any idea of a possible chain reaction is ridiculous. As a matter of fact, I recently spent a full week checking the math again myself, so I know. But we knew how you felt about it, Rothman, and we didn’t want you to be worrying here all alone, in case you’d found out. That’s why we came.”

Rothman was looking out the window. He did not answer. Slowly MacPherson went back to his chair and picked up his cards. “And now how about playing some poker? Rothman, you opened for a blue. What about you, Neill?”

“I’m staying,” said Neill, shoving in a chip. “Always was a gambler. I’m going to stay till the cows come home.”

“What time is it?” Rothman asked. “I haven’t got a wristwatch. They think I might break the crystal and cut my throat.”

MacPherson slammed down his cards and jerked his watch from his pocket. “What does it matter what time it is? Why couldn’t they give you a watch with a plastic crystal? If you have to know, it’s eleven-forty.”

“And thirteen seconds,” added Neill.

“Then it’s already started,” said Rothman.

He leaned his head against the back of his chair and closed his eyes. “It’s on its way now. There’s somewhat more than a third of the Earth between us and Waaku--the place where Waaku was, I mean. The disintegration wave is moving slowly. The seismic wave of an earthquake would get here in about fifty minutes, more or less. But the shock wave from Waaku, traveling somewhere around five thousand miles an hour, will need about an hour and seventeen minutes, plus or minus a minute or so. That means it will reach us in about thirty-seven minutes from now, and the disintegration wave is following close behind. Well, nice to have known you, fellows. Anyone want to check my math?”

He waved toward the desk behind him, piled high with manuscript and a sprawling heap of books on which rested a slide-rule.

“Calm down,” said MacPherson. “Nothing is going to happen. Damn you, Avery! Are you proud of what you accomplished?”

Avery glared. “It’ll do him good! He’s got to learn to face reality, like the rest of us. In a little more than half an hour, the test will be finished. The world will still be here. Rothman will have to admit his equations were wrong--and then he’ll be cured.”

Rothman leaned forward. “Or contrariwise, Rothman will not have to admit he was wrong and Rothman will not be cured! If I made a mistake in my math, why couldn’t anybody put his finger on it? I’m not so crazy that I wouldn’t be able to see an error in calculus when it was pointed out to me. If you’re sure my calculations are wrong, why do you look so frightened?”

“Do we have to go over all that again?” said MacPherson. “The boys at Columbia told you where the mistake was. It’s where you inverted that twelve-by-twelve matrix. Didn’t you bother to check the inverted matrix?”