Hetty Winthrop (played by Patricia Routledge) is a retired working-class woman from Darwen in North West England, who has a knack for jumping to conclusions and solving crimes of varying bafflement which often are too minor concern to the police. Although on occasion her husband offers assistance, he more often than not tends to the home while Hetty gads about the countryside with young Geoffrey in search of resolution and justice. In many episodes Hetty seeks the help and advice of DCI Adams of the local constabulary.
The series is based on characters from the 1986 novel Missing Persons by David Cook (who co-wrote the series with John Griffith Bowen). The incidents in Cook's book were inspired by his own mother's real-life experiences.