Recently retired English professor Harriet "Harry" Wild discovers a knack for investigation and is compelled to intervene in cases assigned to her police detective son.

Due to their new notoriety, Harry and Fergus are approached by a woman desperate to find out how her husband died. Although reluctant to get involved, Harry's interest is soon piqued.

Harry enlists her granddaughter Lola to go undercover at a girls' school in pursuit of a bank robber who committed murder to fake his own death.

Harry and Fergus agree to help a local loan shark known as Happy find out who murdered his employee. In return, Happy will cancel the sizeable debt owed by Fergus' father.

A stuffy dinner party in the home of Harry's former colleague goes awry when a vomiting bug hits all the guests but Harry. After the cause of the sickness is traced to a dead body in the home's well, Vicky Boyle leads the investigation.

A violent storm traps Harry, Fergus and Lola in the local pub. Cut off from the outside world, the trio are put in even more peril when they discover a kidnap victim in a car.