The Man in the Queue — Josephine Tey

A long line had formed for the standing-room-only section of the Woffington Theatre. Didn't You Know?, London's favorite musical comedy for the past two years, was finishing its run at the end of the week. Suddenly, the line began to move, forming a wedge before the open doors as hopeful theatregoers nudged their way forward. But one man, his head sunk down upon 'his chest, slowly sank to his knees and then, still more slowly, keeled over on his face. Thinking he had fainted, a spectator moved to help, but recoiled in horror from what lay before him: the man in the queue had a small silver dagger neatly plunged into his back. So begins Inspector Alan Grant's first spectacular case, and it's up to the dapper detective to discover how murder was committed among so many witnesses, none of whom saw a thing.