The sudden death of a celebrated actress during her own birthday celebration forces Superintendent Roderick Alleyn to investigate a circle of suspects hiding behind masks of adoration. Mary Bellamy, a prominent figure in the British theatre scene, succumbs to a lethal insecticide, turning her festive gathering into a crime scene. Alleyn must navigate the complex social dynamics and professional rivalries of the theatre world to identify which of the guests orchestrated the fatal act. The narrative follows a traditional procedural structure, focusing on the methodical collection of clues and the psychological interrogation of a closed group of suspects.

This work is widely regarded as a quintessential example of the Golden Age detective novel, showcasing the author's deep familiarity with the theatrical world. Readers often highlight the sharp, witty characterizations of the suspects, which provide a satirical edge to the central mystery. The procedural elements are noted for their precision, reflecting the author's commitment to logical deduction and atmospheric detail. The novel remains a staple for those who appreciate the classic British mystery style, where the setting is as vital to the plot as the crime itself.