East Friesian Otto moves to the big city Hamburg. There he gets into trouble with a loan shark and needs to find a way to impress his love interest Silvia.
When another dead elderly gentleman is fished out of the Thames, Inspector David Perkins is convinced that the gorilla gang is active again. On a doll found with the body, characters of an African language are discovered. Together with Sergeant Pepper and language specialist Susan MacPherson, the search for the head of the gang begins.
