The Black Lizard Big Book of Black Mask Stories

Scuffing of feet, and the scratch of chalk on the school board, were the only sounds in the classroom as the students worked out the problems that Cansdale had given them, in order to work out his own.

Having a late-shift program, his last class would be over at five. Cansdale wrote the figure on a piece of paper after making certain that there was no other sheet beneath it and that the hard surface of the marble laboratory slab retained no impression.

At five thirty he could be in the Loop eating in the little one-armed restaurant near the main library on Wabash. By five forty-five he would have received and signed for his books at the library desk. By six he could be lost in the north-bound, rush-hour traffic on the outer drive.

He made a neat time-table of the figures.

By six thirty, six forty-five at the latest, just when the evening dusk was blackest, he could be on his own back porch opening the window with the broken lock.

By seven his wife would be dead, her head battered in with some handy object and her nude body tossed on the bed to simulate an attack by the moronic killer. The absence of strange fingerprints wouldn’t be a stumbling block. The killer always wore gloves. Both doors of his apartment would still be double-locked and barred if he left in the same manner as he entered.

He doubted if Mazie would scream when she saw him. She would be pleased. She could have no idea what he had come for. He continued with the writing of his schedule.

By seven thirty his car would be parked back on Wabash Avenue and he would be in the crowded library reading-room, perhaps exchanging his volume on chemistry for others, to call attention to himself. Shortly after the closing hour of nine he would return to his apartment to find both front and rear doors double-locked and barred. The police, perhaps the stupid fool next door, would help him batter down the door and find the body.

His alibi would be perfect. The thin-lipped, prim, old-maid librarian from whom he always got his books would swear he had been there between the hours of five thirty and nine. She had no reason to doubt it. But no suspicion would be attached to him. He was, in the public eye, a dutiful, loving husband. He had no known motive for wanting Mazie dead. He and Evelyn had been too circumspect. But for the convention week just past he had never seen her oftener than twice a week. They had never appeared in public together. In school they merely nodded and exchanged an innocuous morning note disguised as division business.

The little man’s pulse began to pound as he allowed his thoughts to dwell on the charms of the blue-eyed, blond history teacher. She was a greedy little piece of baggage, combining intelligence with fire. But she was worth the sacrifice, if it could be called a sacrifice, that he was making. With Mazie’s insurance, rings, and furs, there would be enough to satisfy even Evelyn’s capricious tastes for quite some time.

Cansdale stroked his wisp of a mustache and smiled. Most murderers were fools. A lesser man with his knowledge of chemistry would undoubtedly have poisoned his wife and have wound up in the chair. The very manner of the murder he had planned would serve to divert suspicion from him.

Well pleased with his own intelligence the little man memorized the table of figures that he had drawn up, touched the paper to a Bunsen burner, watched it crumple into ash, then sat grinding it to pieces with a pestle.