 Thirty-three-year-old journalist, Jim Holden, is obsessed with the mysterious disappearance of former Australian prime minister, Harold Holt, who went for a swim near Portsea, Victoria on December 17, 1967, never to return. This obsession with Holt s disappearance helps Jim hide from depression, brought into being by the dissolution of his marriage, and an unfulfilled desire to write feature articles. On the thirty-sixth anniversary of Holt s last swim, Jim meets two alluring young women at a pool party, one of them claiming to be Harold Holt s mistress. As the night wears on, Jim finds himself in the backseat of a car, behind the two vintage sirens who have decided to take Jim to Portsea for a midnight swim ....