Clerville, 1960s. The infallible Diabolik, a ruthless thief whose real identity is unknown, has carried out another blow, escaping yet again from a police ambush with another clever trick. Meanwhile, there is great anticipation in town for the arrival of Lady Kant, a fascinating heiress who'll be bringing a famous pink diamond with her. The priceless jewel does not elude Diabolik's attention, who in an attempt to put his hands on it, gets enchanted by the woman's irresistible charm. But now the very life of the King of terror is in danger: Inspector Ginko and his team have finally found a way to draw him out into the open and this time Diabolik will not be able to get out of it alone.