"The Saint", a master criminal turned crime-fighter, and features horror film legend Bela Lugosi as "The Partner".

Co-starring in the film is Helene Whitney as love interest Anne Bitts, and Jonathan Hale as Insp.

The package is sent under the name Simon Templar, but the sender is a man called The Partner, who is a member of an international team of jewel thieves, led by Boss Duke Bates.

Bates himself, posing as Templar due to their uncanny resemblance, comes to visit Professor Bitts and gathers some of the smuggled diamonds.

Fernack realizes that Boss was Templar's double and lets him run after he has returned the stolen jewels he found in the mummy.