Detective Chief Inspector Mercer is called to the scene when a skeleton of a girl is found on Westlaugh Island in the upper reaches of the River Thames. What appears to be a straightforward and routine investigation, however, leads to unexpected events and a string of unlikely characters, including a lawyer and a one armed garage proprietor. Nothing seems to fit together and it seems the sleepy town holds many secrets. The finale involves two nights of dramatic violence and it isn't until this stage is reached that the twisted truth finally emerges.