Horace Dorrington solves the mystery of a case of sabotage on a bicycle track.

Horace Dorrington clears up the mystery of the theft of a valuable diamond.

Conman and invesigator Romney Pringkle exposes a swindle and makes a profit.

Professor Van Dusen, the 'Thinking Machine', boasts that he can think his way out of a prison cell. When he is locked up he is given the chance to prove that he can escape by the power of his mind alone.

Professor Van Dusen must find out why a young woman had a perfectly healthy finger cut off by the eminent surgeon Prescott.