Boris Karloff stars as master criminologist Colonel March, who heads The Department of Queer Complaints, investigating bizarre crimes that challenge logic and reason.
When a psychologist is found stabbed to death in a seemingly sealed room, Inspector March must decide who had a reason to kill him, and how the person accomplished the task.
Members of the Himalayan Mountaineering Club are threatened by what appears to be the abominable snowman, and someone leaves a strange footprint on a ledge outside Colonel March's office.
Colonel March's niece, a believer in spiritualism, thinks she hears her dead husband's voice, and others in the house become convinced her husband has returned as a ghost.
Colonel March is called in to investigate the theft of a valuable diamond, as well as the kidnapping of a little boy's poodle; as the investigation continues, he begins to think both incidents may be connected.
When a woman reports her reclusive mystery writer husband has accidentally fallen from a cliff, suspicion points to her as the killer; Colonel March is called in to investigate at the isolated seaside manor.
While on holiday in France, there is a murder at the docks and Colonel March is asked by a friend of the French police to assist; the only clue left behind by the culprit is a sailor's cap, setting off a search for the head that fits the hat.
At an isolated château outside Paris, a scientist insists he has received radio waves emanating from Mars; seeking a way to suspend a person's life functions during space travel, his volunteer subject dies from lack of oxygen.
Colonel March and Inspector Goron are present in a cafe when a customer dies from poisoned wine; the waiter falls under suspicion because he was a former chemist.
A man demands to be arrested for plotting the perfect murder of his wealthy wife, who is found dead that night of natural causes; a valuable coin collection holds the answers.
A shady businessman collapses on an oceanside jetty, the apparent victim of a heart attack, but a vacationing March discovers blood and a needle near the body; a boy's lost ball may be the key to a possible murder.
After a bank robbery, the suspect is followed to his office, but when March and the authorities arrive and search the office there's no trace of the money.
A 15th-century prayer volume disappears from a sealed casket inside the locked safe belonging to an Oxford Don; an illusionist is called in to demonstrate how the book can disappear from a locked safe, when the supernatural is suspected.
A barmaid receives an unusual Christmas gift -- a music box from a thief who has been dead for 10 years -- but someone is soon murdered searching for something valuable hidden in the mysterious gift, and Colonel March thinks the music holds the key.
A phony spiritualist believes she has truly summoned a real ghost; Colonel March attends her next seance to discover the identity of the spirit's killer -- dead or alive.
Colonel March receives an unusual complaint that a pair of disembodied gloves killed a man; he refuses to give up easily, despite the fact there is no corpse, no blood, and no evidence of wrongdoing.