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.
Karin Twerdy used to be an opera singer but now, in order to pay for her daughter Daniela's education in a religious school, she performs in a shady nightclub. Industrialist Dietrich Gontard, the father of Karin's school friend Christa, falls for her. But when he learns the truth about her he is outraged and rejects her. At a loss and not to stand in the way of Daniela's future, Karin chooses to disappear...
