Diabolik (John Phillip Law) is the criminal mastermind who has just pulled off a huge heist. He spends most of his free time with his girlfriend, Eva (Marisa Mell), in fond embrace. The police minister (Terry-Thomas) is approached by Valmont (Adolfo Celi), a master criminal who proposes to use his underworld connections to catch Diabolik for the police. In between their gratuitous lovemaking, he and the exotic Eva are chased by police and the mob in this plodding crime drama.
~ Dan Pavlides, All Movie Guide