Transcriber's Note: This etext was produced from Space Science Fiction May 1953. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed. INSTANT OF DECISION BY RANDALL GARRETT ILLUSTRATED BY EBEL How could a man tell the difference if all the reality of Earth turned out to be a cosmic hoax? Suppose it turned out that this was just a stage set for students of history? When the sharp snap of a pistol shot came from the half-finished building, Karnes wasn't anywhere near the sandpile that received the slug. He was fifteen feet away, behind the much more reliable protection of a neat stack of cement bags that provided cover all the way to a window in the empty shell of brick and steel before him. Three hundred yards behind him, the still-burning inferno of what had been the Assembly Section of Carlson Spacecraft sent a reddish, unevenly pulsating light over the surrounding territory, punctuating the redness with intermittent flashes of blue-white from flaring magnesium. For an instant, Karnes let himself hope that the shot might be heard at the scene of the blaze, but only for an instant. The roar of fire, men, and machine would be too much for a little pop like that. He moved quietly along the stacked cement bags, and eased himself over the sill of the gaping window into the building. He was in a little hallway. Somewhere ahead and to his left would be a door that would lead into the main hallway where James Avery, alias James Harvey, alias half-a-dozen other names, was waiting to take another pot-shot at the sandpile. The passageway was longer than he had thought, and he realized that he might have been just a little careless in coming in through the window. With the firelight at his back, he might make a pretty good target from farther down the hall, or from any of the dark, empty rooms that would someday be officers'. Then he found it. The slight light from the main hallway came through enough to show him where to turn. Keeping