Archibald Marshall faces a terrifying fate as he approaches his 30th birthday. His two brothers died within days of their own 30th birthdays, leading him to suspect foul play.

He seeks the help of Decius Hamill, a crime prophet, and his young assistant, Mr. Slade, to uncover the truth. As they delve into the mystery, they discover that a mastermind is behind the deaths, and they must act quickly to prevent Marshall's death. With clues in the form of a drugged and unconscious victim, a padded rope, and a swinging pendulum-like motion, can they stop the killer before it's too late?