Enter A Murderer by Ngaio Marsh

In this gripping mystery, a theatrical production takes a deadly turn when a prop gun is swapped for a real one, resulting in the on-stage murder of an actor. The audience, initially believing it to be part of the performance, is soon engulfed in chaos as the truth unfolds. The astute Inspector Roderick Alleyn is called to the scene, where he must navigate the complex web of backstage rivalries, hidden motives, and personal vendettas to uncover the identity of the killer. As the investigation progresses, secrets are revealed, and the line between performance and reality blurs, leading to a dramatic and unexpected conclusion.