Chief Detective Inspector Benedict Mitchell refuses to go with his wife to their old school where a party is being held in honour of the headmaster, who is now retiring. Consequently, when one of the departing guests is killed by a hit-and-run driver, Mitchell's wife is the only witness. And Virginia is adamant that the driver hit Donald Markey intentionally. For twenty-four hours the incident is treated as murder. However, no confirming evidence of intent turns up and no one seems, in Superintendent John Carroll's view, to have sufficient motive to take such a risk. The enquiry is officially scaled down and the hunt is now merely for a driver who failed to stop after causing a fatal injury. Backed up by his team of officers, Mitchell ignores his superintendent's instructions and continues a clandestine and unauthorised investigation into the victim's womanising, his financial dealings and his relationship with his extremely wealthy wife. It transpires the chief suspect is Virginia's former school friend who has now fallen on hard times and Virginia is determined to help her, even concealing evidence which may have led to her arrest. When Mitchell finds out, great strain is placed on the marriage. Yet in typically impulsive and ebullient fashion, Mitchell determines to solve the crime, save his marriage - and satisfy his demanding superintendent.