It had taken months for Janine McQuarrie to succumb to her husband's pressure to have sex with strangers at suburban spouse-swapping parties. But after attending a few such events on the Mornington Peninsula, this Australian social psychologist rebels. And then, driving with her young daughter one day, she gets out of her car to ask directions from another driver, is killed. The little girl escapes when the gunman's pistol misfires.
Inspector Hal Challis, to whose Crime Investigation Unit the case falls, is thwarted in his efforts by his boss. The dead woman was Superintendent McQuarrie's daughter-in-law. 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? The villain turns out to be someone Challis never would have expected.