Yvonne is scandalised to discover that her beloved son, Michael, is intent on marrying Madeleine, who he says is having an affair with a mysterious older man. At the same time, George, Michael's father, confides in Yvonne's sister, Leo, that he is in fact Madeleine's other lover. Together, they hatch a plot to end Madeleine's hopes of marriage - by threatening to reveal George's secret to his son.