It takes months for Australian social psychologist Janine McQuarrie to succumb to her husband’s pressure to attend spouse-swapping parties, but eventually she gives in. Then, driving with her young daughter one day, she gets out of her car to ask directions and is shot and killed. The little girl escapes when the gunman's pistol misfires.
 Inspector Hal Challis of the Crime Investigation Unit is assigned the case, but his efforts are thwarted by his boss. The dead woman was Superintendent McQuarrie’s daughter-in-law, and he  seems to be more interested in protecting his son than in finding his daughter-in-law’s murderer. Who might have a motive to kill this attractive young wife and mother? One of her clients? One of the swingers she’d gotten together with at a party? Or, the obvious suspect, her husband?