Lord James Harrington and his wife, Beth, happen upon a road accident where the driver, Bernard Potter, is seriously injured. While giving first-aid, Potter mumbles concerns about his daughter which James takes as the ramblings of a dying man. But, when visiting Mrs Potter, they realise that her husband, a police constable, was secretly investigating the goings-on at a local commune where his daughter lived. Meanwhile, James' cousin, Herbie, is helping Scotland Yard with an art fraud ring that has extended its reach into Sussex. And, when GJ is approached to be a part of that enterprise, James is drawn into both investigations.