Sophisticated woman-of-the world Adela Bradley [Diana Rigg] and her chauffeur George Moody [Neil Dudgeon] are an unlikely pair of investigators back in the England of the 1920s. Free from her boring husband, Adela tours England but always stumbles onto murder and mystery. Although she is the primary detective, she relies on George to get information to help her solve the case.
A knife-thrower's assistant with a travelling circus is found stabbed to death. At Inspector Christmas's invitation, Mrs. Bradley and her chauffeur, George, infiltrate both village and circus communities in an attempt to solve the murder.
Mrs. Bradley accompanies her chauffeur, George, to his daughter's wedding. Local fishermen discover the body of the vicar's daughter on the beach, with her hair shaved off and a worsted viper around her neck.
Mrs. Bradley returns to her old school to give the prestigious Evadne Flint Lecture, but the school music teacher is found dead during a performance of The Mikado. Mrs. Bradley investigates, and uncover bitter rivalries, a series of thefts, an illegitimate child, and a number of illicit affairs.
Mrs. Bradley attends a party to celebrate the engagement of her god-daughter, Eleanor Bing, to Everard Mountjoy. When Everard meets with an untimely death, the police conclude that it was a tragic accident. Mrs. Bradley is unconvinced and, aided by her trusted chauffeur, George, sets out to discover the truth. (Pilot)