It starred George Hilton, Anita Strindberg, Ida Galli and Janine Reynaud, and the music soundtrack was by Bruno Nicolai.

In London, Lisa Baumer, who is engaged in an extramarital affair with George Barnet, is informed that her husband Kurt has died in a plane explosion en route to Tokyo and that she will receive a life insurance payout of one million dollars in Athens.

Afterward, Stanley discovers a scorpion-shaped cufflink on the floor.Lisa's lover Barnet is murdered in an Athens hotel room belonging to his mistress; the pair are revealed to be flight attendants.

They arrange for Peter to take a vacation with Cléo in the Saronic Gulf, pretending that he is a fugitive from justice in order to lull Kurt into a false sense of security.

Peter apprehends her and takes her back to the boat, where he reveals that he plotted the deaths of Kurt and Lisa with Barnet to claim the insurance payout while making it seem that Kurt faked his own death, stole the payout from Lisa, then killed her, Lara, Sharif, and Barnet to cover his tracks.

He also had Barnet attack Cléo and leave behind the scorpion cufflink as part of the effort to make the authorities suspect Kurt.

They deduced Peter's scheme from Barnet's mistress's mermaid brooch of similar make to the scorpion cufflink, which was a counterfeit of Kurt's.

[4][failed verification] Adrian Luther Smith wrote that the film is "....one of the best of Sergio Martino's impressive batch of thrillers.

It has considerable energy, some pleasing exotic locations and is crammed with a great cast of shady characters.....The resulting gory carnage is graphically presented.