In the shadowy streets of Soho London, a sinister force is stirring once more. When another elderly victim is found dead in the Thames, Inspector David Perkins is convinced that the notorious gorilla gang is back on the loose, leaving behind only cryptic clues and a trail of terror. As Perkins teams up with language specialist Susan MacPherson to track down the gang's leader, the investigation becomes a perilous cat-and-mouse game through the dark underbelly of the city.