Sydney homicide detective Sergeant Scobie Malone (Jack Thompson) and his offsider Shane Porteous investigate the murder of Helga (Judy Morris), whose corpse is found in the basement of the Sydney Opera House. Malone had met Helga previously and discovers she was a high class prostitute who was also a mistress of the Minister for Culture (James Workman) and involved with film director Jack Savannah (Joe Martin). In flashback it is shown that Helga was blackmailing the minister and his wife (Jacqueline Knott), along with a crime boss, Mr Sin (Noel Ferrier).
Eventually it is revealed that Helga was killed while fleeing Captain Bixby (Cul Cullen). Malone becomes convinced of the guilt of the Minister, but powerful influences intervene and he gets off. The Minister resigns, citing ill health, and travels to Europe with his wife. Malone criticises his boss, Inspector Fulmer (Walter Sullivan) and is suspended for insubordination for ninety days. Fulmer later suggests he come back, but Scobie elects to stay by the pool for the full ninety days.