A girl is found dead on a seat in an underground railway train. Journalist Polly Burton attempts to solve the case.
Inspector Lipinski is placed in charge of the investigation into the theft of a 500 carat diamond.
Professor Van Dusen, aka the Thinking Machine, brags that he can think he way out of a prison cell.
Laxworthy and two pals find themselves having to protect the safety of French torpedo plans from enemy agents.
French detective Eugene Valmont tries to break up a counterfeiting ring.
A Danish lieutenant comes to the aid of a Russian countess who claims that her brother-in-law plans to murder her.
Why did a young damsel have a perfectly good finger removed during an operation performed by an eminent surgeon? That's the question for Professor Van Dusen, aka the Thinking Machine.
Dagobert Trostler investigates a case of poison pen letters in turn-of-the-century Vienna.
In order to prevent the assassination of a Russian Grand Duke, Dr. Thorndyke must decipher a difficult code.
William Drew, an agent of the foreign office, finds himself assigned to investigate a most unusual crime.
The aftermath of a sensational murder trial sends Charles Dallas on an eerie and dangerous adventure.
The purser of an ocean liner tries to recover gold which has disappeared from the storeroom of his ship.
A gypsy sets out to prove that a police detective is wrong about who killed a woman. Who murdered Mrs. Arryford? The answer is obvious to detective sergeant Grubber - but not to Hagar the gypsy. It takes all of her gypsy intuition to arrive at the solution.