Agatha Christie, Dorothy A. Sayers, Gladys Mitchell - the three grand dames of the golden age of the English detective story, the founder of the legendary Detective Club. Gladys Mitchell remained in the shadow of her famous contemporaries for a long time. However, today her books about the investigations of the eccentric Mrs. Bradley are experiencing a rebirth. Many of them have been filmed by the BBC.

Maths teacher Miss Ferris from a prestigious school is killed right before she goes on stage in an amateur performance. But who could want her dead? Fellow teachers she knew too much about? A longtime admirer, with whom Miss Ferris carefully hid her relationship? Mrs. Bradley begins an investigation - and comes to completely unexpected conclusions...