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.
A French fashion model asks for Colonel March's help, claiming a strange man is following her and she fears for her life; several hours later, she's found murdered -- in mismatched color, a telling clue for the inspector.
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.
March must solve the mystery of how a man could be stabbed to death by an invisible knife while attempting to summon the devil during a black rite.
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.
The Second Mona Lisa, painted six months after the first, is targeted by rival collectors; Colonel March is determined to reveal the truth.
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.
A 12-year-old boy insists that his dead father told him to kill his mother's new fiance, but the dad may not have truly perished in a plane crash.
Colonel March hypnotizes five people to solve the stabbing murder of Lord Telford, while he portrays the murder victim.
Colonel March investigates a murder in a beauty salon; there are plenty of suspects, and it's up to him to single out the killer.
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 cancer research scientist believes his test monkey was not only stolen but replaced; he is later found dead in what may have been a suicide.
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.
Behind the silver curtain spray from a fountain, a man is found dead with a knife in his back; Colonel March is called in to investigate.
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 skull, known as the Damascus man, is stolen from a museum, and Colonel March's life is imperiled trying to solve the case.
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.
Murder and blackmail culminate when a call for help during a Javenese dance is the clue that Colonel March needs to prove a faulty alibi.
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.
When a woman is found dead in London, Colonel March must determine whether it was suicide or murder; a French fencing match holds the vital clue.