The Nine Mile Walk by Harry Kemelman

A casual remark during a conversation—“A nine-mile walk is no joke, especially in the rain”—leads a professor of logic to deduce a crime no one knew had occurred. As he follows the implications of that single line, the pieces of a robbery and murder come together with stunning precision. The plot is built entirely from deduction and conversation. A brilliant and minimalist mystery that showcases the power of logic. A short but unforgettable puzzle.