The Frog is a master criminal who is sought both by the police and by an amateur American sleuth and his comical butler/sidekick. The Frog falls in love with a young woman and hatches a ridiculous Rube Goldbeg-like plot to get her to give herself him. He uses a singing siren named "Lolita" to ensnare her ne'r-do-well brother into a gruesome murder plot. The brother is convicted of the capital crime and sentenced to death only to find the executioner is someone very familiar to him.
As other have said, this is the first of West German Edgar Wallace krimis. It's certainly not the best, but it is pretty entertaining. The comical sidekick (here played by Eddie Aren't) would become a staple of this series, to the annoyance of some, but personally I don't think this kind of comedy really hurts these films that much because the plots are already delightfully absurd and villains like the Frog are more than a little cartoonish to begin with(but I mean that in a good way). The butler/sidekick here kind of anticipates (perhaps even influenced?) the "Kato" character in the "Pink Panther" series in that he is always sparring with his boss to keep him sharp. The bigger liability here, however, is the "American" protagonist himself. But Joachim Fuchsberger, who was in nearly all these movies, would get a lot better in the future entries in the series, especially when he got to play an "English" detective (a role at which the German actor was much more convincing).
But in addition to the serial-comic strip elements of the plot, there is also a little bit of raciness courtesy of "Lolita" (Eva Pflug), and some surprisingly gruesome violence--the centerpiece murder and a scene where the Frog very violently dispenses with one of his accomplices. In any event, if you enjoy the German krimi series (or the later but the closely related Italian gialli), you certainly won't want to miss this first one.
