A man is killed when a speed boat is deliberately driven into the back of his vessel. A friend who was with him at the time identifies the person responsible as a well-known crime figure and an old enemy of Frank's: Marty Miller (Peter Kowitz). Sykes takes part in a training course for police divers. Goldie and Knocker seem to get along very well, and a vietnamese cleaner, Thong, is found dead at the Water Police headquarter.