The Monster of London City

London, 1929. Frank Webber, a very busy Scotland Yard detective, seems to be more interested in his work than in Alice White, his girlfriend. Feeling herself ignored, Alice agrees to go out with an elegant and well-mannered artist who invites her to visit his fancy apartment.

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.

After an innocent man is executed in a case he was responsible for, a Scotland Yard superintendent finds himself investigating the murder of his key witness.

A woman recovering from a nervous breakdown tries to convince her husband and and the local London police that she has witnessed a murder in the abandoned house next door.

Master car thieves square off against French gangsters in the South of France with money, women and lives all on the line.