Private investigator Michael Shayne [Lloyd Nolan] and his singer fiancée Joanne La Marre [Mary Beth Hughes] are staying in a hotel when a woman’s scream tears through a closed door. The hotel maid, Emily, has discovered two dead people in a room: Louis Lathrop, the hotel and theater owner, and Desiree Vance, one of Lathrop’s leading actresses. Both are dressed in medieval costumes, and Lathrop’s headgear is the dog‑head from a prop, a baffling detail that sets the stage for a twisting, old‑fashioned whodunit.
Police inspector Pierson [William Demarest] arrives and questions the hotel’s manager, Hal Brennon [Charles Arnt], who explains that the costumes come from Lathrop’s long‑ago show, Sweethearts of Paris. Desiree had been the show’s brightest star, and Carlo Ralph had played Beppo the Dog; Shayne can’t help but suspect Carlo given the curious dog head and the history of the production. The room’s atmosphere hints at secrets, and Shayne’s instincts tell him there’s more to the murder than a simple crime of passion.
As the investigation unfolds, the cast’s interwoven loyalties come into sharper focus. David Earle [Charles Trowbridge], another actor in the same show, reveals that Lathrop had hosted a private party to celebrate the production’s anniversary, hinting at old grievances and hidden motives among the troupe. Shayne starts to map the social web around Lathrop, mapping out who stood to gain from his death. He learns that the musical director was Max Allaron [Milton Parsons], a man with a notoriously drinking problem who also resides at the hotel, deepening the mystery with a personal angle that could blur the lines between patronage and betrayal.
The plot thickens when Shayne discovers that Lathrop kept another woman in addition to Desiree, and that the apartment within the building has many entrances and exits—an architectural detail that could conceal a killer or a hidden motive. From Earle’s daughter, Shayne learns that Julian Davis [Henry Daniell], another cast member, had stolen money from Lathrop. He pays a visit to Davis and finds him in the company of Phyllis Lathrop [May Beatty], Louis’ wife. They confess to embezzling funds but insist they are innocent of murder; they hire Shayne to help them prove it, complicating the detective’s case with two seemingly legitimate clients who are not entirely trustworthy.
Shayne pushes deeper, interviewing Allaron and uncovering a chilling contradiction: Carlo Ralph, presumed dead after World War I, appears to have a living‑and‑well cousin in the present, supported by a letter found in Desiree’s room. This revelation unsettles the timeline and casts doubt on the suspects who thought they understood Carlo’s fate. The detective’s persistence leads to a dramatic team effort—Davis is brought to the Lathrop apartment, and a hidden passage to Emily’s room downstairs is exposed. The trio discovers Emily’s body and a note explaining that she had killed Lathrop years earlier after he betrayed her for another woman. Emily, it turns out, was once known as actress Lynne Evans Lynne Evans, a twist that aligns with the theater’s tangled past and reinforces the sense that the show’s history is literally coming back to haunt its people.
Despite the mounting evidence, Shayne remains wary—he suspects Emily did not commit suicide and keeps digging. Back in Lathrop’s apartment, Pierson is knocked unconscious by Allaron in a calculated move that aims to derail the investigation. The quiet arrival of Otto Kuhn [Erwin Kalser], the theater doorman, introduces a new and explosive confession: Otto is Carlo, the former husband of Desiree who was left for Louis Lathrop. Carlo’s motive intertwines jealousy, betrayal, and financial pressure, and he admits to killing Desiree and Lathrop. He also admits to killing Emily, because she had learned too much about him. The confession clarifies the killers’ identities, but it also raises questions about who was truly in control of the theater’s dark history. Allaron had been blackmailing Carlo, using the threat of exposure to extract money and loyalty, and he was seen leaving the apartment just after the killings, a clue that helps piece the puzzle together.
In a climactic confrontation, Pierson regains consciousness and, with Shayne, brings Otto and Allaron to account. The evidence unravels the web of lies and greed that entangled the case, exposing a layered conspiracy: a mix of embezzlement, obsession, blackmail, and one‑time romance that spiraled into murder. With the case finally resolved, Shayne asks Pierson to stand as his best man at his wedding that very day—a reminder of the lightness that still exists beyond the noir shadows. But the scene takes an unexpected turn when Joanne, waiting for Shayne, reveals she has eloped with her former boyfriend, a decision that ends their immediate plans and leaves Shayne alone with the memory of the case and the consequences of waiting too long.
The hotel’s corridors, the show’s dusty prop rooms, and the hidden doors of the past all serve as a stage for a mystery that refuses to stay buried. The story blends classic noir tension with a backstage‑drama vibe, using the theater itself as a character—its costumes, its secrets, and its ghosts guiding every twist. The investigation moves with a careful pace, never rushing to judgment, and each revelation reframes what the audience thought it knew about loyalty, love, and the price of keeping dangerous truths hidden. The finale ties together the disparate strands—blackmail, theft, old loves, and present danger—leaving viewers with a satisfying but morally complex resolution that honors the era’s penchant for stylish whodunits with a touch of melodrama.
