CHAIN REACTION By BOYD ELLANBY Illustrated by DOKTOR [Transcriber's Note: This etext was produced from Galaxy Science Fiction September 1956. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] Would this be the last poker game--with all life at stake and every card a mere deuce? 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.