When Brian Cartwright receives a written death threat, he takes it seriously - in his not unblemished past he has made some bitter enemies. So he calls in the famous criminologist Dr. Morelle to protect him. The threatening note has predicted the exact time he's to die - nine p.m. later that same day. As the hour approaches, Cartwright locks himself alone in his study, all doors and windows sealed, with Dr. Morelle and his previously invited house guests in an adjoining room - also locked. Yet when Dr. Morelle re-enters the study after the appointed hour, he finds Cartwright's body slumped on his desk, shot neatly through the head - and not by his own hand! Two classic cases in a long-running series.