MISTAKE INSIDE By JAMES BLISH [Transcriber's Note: This etext was produced from Startling Stories, March 1948. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] This was England, two hundred years before bomb craters had become a fixed feature of the English landscape, and while the coffee house still had precedence over the pub. The fire roared, and the smoke from long clay church-warden pipes made a blue haze through which cheerful conversation struggled. The door swung back, and the host stood in the opening, fat hands on hips, surveying the scene contentedly. Someone, invisible in the fog, drank a slurred uproarious toast, and a glass slammed into the fireplace, where the brandy-coated fragments made a myriad of small blue flames. "Split me if that goes not in the reckoning!" the innkeeper bellowed. A ragged chorus of derision answered him. The inn cat shot down the stairs behind him, and its shadow glided briefly over the room as it passed the fire. It was an impossibly large, dark shadow, and for a moment it blacked out several of the booths in the rear of the chamber; the close, motionless air seemed to take on a chill. Then it was gone, and the cat, apparently annoyed by the noise, vanished into the depths of a heavy chair. The host forgot about it. He was accustomed to its sedentary tastes. It often got sat on in the after-theater hilarity. He rolled good-naturedly across the room as someone pounded on a table for him. But the cat, this time, had not merely burrowed into the cushions. It was gone. In the chair, in a curiously transparent condition which made him nearly invisible in the uncertain light, sat a dazed, tired figure in a Twentieth-Century Tux.... The radio was playing a melancholy opus called "Is You Is or Is You Ain't, My Baby," as the cab turned the corner. "Here you are, sir," croaked the driver in his three A.M. voice. The sleepy-eyed passenger's own voice was a little unreliable. "How much?" The fare was paid and the cabby wearily watched his erstwhile customer go up the snow-covered walk between the hedges. He put the car in gear. Then he gaped and let the clutch up. The engine died with a reproachful gasp. The late rider had staggered suddenly sidewise toward the bushes--had he been that drunk? Of course, he had only tripped and fallen out of sight; the cabby's fleeting notion that he had melted into the air was an illusion, brought on by the unchristian lateness of the hour. Nevertheless the tracks in the snow did stop rather unaccountably. The cabby swore, started his engine, and drove away, as cautiously as he had ever driven in his life. Behind him, from the high tree in the yard, a cat released a lonely ululation on the cold, still night. The stage was set....