Columbo (1971)

You watch the murder in the opening minutes, so the fun is never who but how: how Peter Falk's rumpled lieutenant, with his raincoat, cigar and "just one more thing," will needle a smug rich killer into the mistake that convicts them. The crimes are tidy, bloodless affairs among Los Angeles mansions and studios, and the cat-and-mouse conversations are as satisfying as any drawing-room reveal. Choose it when you want the gentlest suspense on this list, since the outcome is certain and only the method is in doubt.