The dramatic season of 192- opens in a disheartening manner under a misty September rain in New York City. At the Roman Theatre, a packed audience eagerly watches the loud crime melodrama entitled Gunplay, filled with stage gunfire and explosive dialogue. During the performance, a quiet tragedy unfolds in the dimness of the left orchestra. A quiet bookkeeper named William Pusak, attempting to leave his seat during an exciting moment, discovers a man slumped between the rows.
The victim, who is soon identified as the notorious and corrupt lawyer Monte Field, gasps out that he has been murdered before dying in Pusak's arms. Patrolman Doyle immediately takes charge, sealing all exits and summoning reinforcements, including the mild-mannered Inspector Richard Queen and his observant son, Ellery Queen. The investigation quickly reveals that the murderer must be someone who was present in the theatre during the second act.
The police find no trace of a weapon, and an initial examination by a doctor suggests poisoning by an unusual form of alcohol. As the interrogation of the audience yields a series of complex personalities—including a threatened law partner, a secret fiancée, a shady theater usher, and a menacing gangster—the investigators realize they are dealing with a meticulously planned crime. A central mystery emerges around Field's missing silk top-hat, which appears to have been deliberately removed from the scene. The Queens delve deep into the dark past of the deceased lawyer, uncovering layers of blackmail, hidden financial troubles, and old rivalries. As the toxicological reports reveal a startling and deadly poison, the detectives must piece together a tangled web of clues to unmask a clever killer who managed to vanish in plain sight.