b/w The "Frog with the Mask" spreads fear and terror on London's streets. Wrapped in a wide hooded coat, his face hidden under a cover from which only two huge, terrifying eyes shine, he looks for innocent victims together with the members of his gang. Inspector Elk of Scotland Yard has his hands full, because there are almost no traces at the scenes of horror - only on the wrists of the murdered you can find the black sign of the "frog gang". But private detective Richard Gordon and his butler also go hunting...