Several employees on a nobleman’s estate show up at a former abbey, reputed to be haunted, to search for a hidden treasure. Howver, a mysterious hooded figure begins killing off those who may have figured out where the treasure is hidden.

The sister of a famous, but as yet uncaught, criminal named The Hexer is murdered. Inspector Higgins of Scotland Yard believes that The Hexer will surface to take his revenge on his sister’s killers, and plans to set a trap to finally capture him. However, soon bodies start piling up, and it looks as if The Hexer may get away yet again.

Both Scotland Yard and an amateur American sleuth are tracking a master criminal known as The Frog. This moniker refers to the bulging-eyed mask worn by the evildoer, and is reflected by the frog icons painfully tatooed onto the forearms of his henchmen. The trail leads to the country manor of an enigmatic, steely-eyed nabob, whose repressed son has eyes for the artistes at the Lolita cabaret, and whose lovely daughter captures the fancy of both the American playboy and the villain himself. Murder, kidnapping and seduction ensue.