A psychologist is found stabbed to death in a seemingly sealed room. Inspector March needs to decide who had the most reason to kill him, and how did they accomplish the task.

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. But has he?

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 colour, a telling clue for the inspector.

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, a sailor's cap - "looking for the head that fits this hat."

Two Mona Lisa paintings appear on the art market | but which one is the second original and which is the copy? Colonel March is determined to reveal the truth.

At an isolated château outside Paris, a scientist insists he's 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. Accident or foul play?

A 12 year old boy insists his dead father told him to kill his mother's new fiancée. But did the father truly die in an accidental plane crash?

Colonel March hypnotises five people to solve the stabbing murder of Lord Telford, while he himself portrays the murder victim.

Colonel March is called in to investigate a murder in a beauty salon. There are plenty of suspects and it's up to Colonel March to single out the murderer.

Colonel March and Inspector Goron are present in a café when a customer dies from poisoned wine and the waiter falls under suspicion because he was a former chemist.

A scientist conducting cancer research is convinced that his test monkey was not only stolen but replaced. He is later found dead from gas, and Colonel March must prove if it was suicide or not.

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 little boy's lost ball may be the key to a possible murder.

A bank robbery takes place and the suspect, never out of sight, is followed to his office, where he locks himself in. But when the police and Colonel March search his office there is 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 pretty barmaid receives an unusual Christmas gift, a music box from a thief, dead ten years. But someone is soon murdered searching for something valuable hidden in the mysterious gift and Colonel March believes the music holds the key.

A phony spiritualist believes she's 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 in this episode where a call for help during a Javenese dance is the clue that Colonel March needs to prove a faulty alibi.

Colonel March receives a queer 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.

A woman is found dead, but was it suicide or murder? A French fencing match provides the telling clue and Inspector Goron travels to London to assist Colonel March.

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.

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 wife 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.