The crooked Abdul Graner has stolen a priceless diamond from the Louvre and is now awaiting an expert to come to his villa in the Canary Islands to cut the diamond for him. Unbeknown to Graner this is the Saint, working for the police. Christine Graner, Abdul's wife, tells the Saint that her husband is a brute and she wants to leave him, along with the Saint and the diamond, but the Saint feels obliged to continue with his deception. Although Graner is unaware of the Saint's true identity he has his suspicions and forces him at gunpoint to cut the stone whilst holding Christine hostage.