Journalist Terry Nichols [Frederick Brady] is hired by his boss, Sampler [Arthur Loft], to investigate a cryptic letter sent to the Morning Chronicle from Cora Williams [Vera Lewis]. In the letter, Cora claims she has uncovered a $200,000 fortune and insists it proves the murder of Eric Goran, a death deemed a suicide fifteen years prior. Cora’s relative, Walter Elliott [Jonathan Hale], who was once a suspect in that case, is now campaigning for the United States Senate against Sampler’s brother-in-law. Terry, who is dating Walter’s daughter, Gay [Lois Collier], is hesitant but ultimately agrees to take the job. During a preliminary interview, Walter maintains that he played no part in Eric’s death, setting a tense family backdrop for the investigation.
Walter then brings in his lawyer, Tom McGalvey [Douglass Dumbrille], who quickly proposes enlisting a seasoned detective, Ken Grady [Paul Kelly], who previously looked into the case. With the case gaining political heat and personal risk, Terry and his photographer, Pidge [Noah Beery Jr.], stow away on a boat and travel to a remote island to reach Cora’s mansion. There, the Elliots, Tom, and Tom’s assistant Connie [Rose Hobart] have convened in a crumbling residence that seems to hold more questions than answers. The mansion scene opens on a disturbing tableau: Cora lies unconscious in a room with her black cat prowling nearby, and the atmosphere is thick with secrecy and fear. Gay’s bid to summon a doctor is thwarted when the boat they used to travel to the island catches fire, leaving the group stranded in a desperate, stalled pursuit of truth.
Inside, Ken is called upon to sift through alibis and motives while Connie, who suffers from ailurophobia, recoils at the mere sight of the cat. Then Cora dies, and a roomful of people becomes both suspect and witness to a perplexing sequence of events. Ken begins questioning everyone, but their interrogation is interrupted by the arrival of Kyra Goran [Iris Lancaster], an aspiring actress who presents herself as Eric Goran’s daughter and comes to confront Cora about her father’s death. The tension thickens as Gay discovers Ken’s business card bearing Cora’s last words, and attempts to compare it with Connie’s handwriting—only to be bludgeoned from behind. Connie, fearful of becoming a principal suspect, tries to confess but then flees; moments later, she is found dead. When Gay comes to, the card has vanished, and Ken admits he took it.
In a bold, risky gambit, Terry plants a thousand-dollar bill near the [Smokey] cat, staging a scene that suggests the animal has pinpointed the money. Kyra buys into the notion that the feline might be possessed by Cora and could guide them to the fortune. The house divides as everyone searches for the supposed “little house” where the money might be hidden. Gay ventures into the basement in search of a childhood dollhouse she once owned, and follows Ken down the stairs. An unseen assailant trips Ken, who is impaled on a rake, leaving the group to question Walter’s involvement once more. As they emerge from the basement, the cat remains hovering above the dollhouse, a silent, eerie symbol of the mystery.
Terry later discovers Tom rummaging through the same dollhouse for the hidden money, and a confrontation ensues. Tom finally confesses to a bootlegging operation that Eric Goran had helped run out of Cora’s mansion years ago. He and Eric allegedly cooked the books and planned to leave with the profits, but Eric was murdered and the money hidden elsewhere when the operation dissolved. Tom had tried to escape with the profits but could not locate the cache on the island. Ken and Connie, who had learned of Tom’s scheme, had used it to leverage him, adding pressure to reveal the truth. Terry then reveals a crucial twist: Kyra is not Eric’s daughter but an actress hired by Terry to pressure the murderer into revealing their identity. In the final turn of fortune, Pidge discovers the fortune hidden inside a birdhouse outside Cora’s bedroom window, bringing the case to a close as the tangled web of deceit unravels.
