The Marilyn Monroe in question is a beach donkey and Grace Smith - too broke to be selective when it's a question of work - is called in by the donkey's owner, Drysdale, to investigate this bizarre crime. While doing so she finds herself inexorably drawn into the mystery surrounding the murder of a young woman, Tina, whose aunt lived in the house backing on to Drysdale's land. As the plot unfolds, it becomes clear that the murders of Marilyn and Tina are connected - and that Grace has stumbled on a whole lot more than she bargained for . . .