Joan Sheridan returns home from her first sea voyage only to discover that her stepbrother Kirklan has married a beautiful woman named Helen. Displaced from her room and harboring deep feelings for Kirklan, Joan struggles with her resentment. Meanwhile, Helen receives a smudged letter from a disreputable figure named Don Haskins, a criminal from her past who demands a thousand dollars as the price of his silence. Helen manages to secure a promise of the money from her doting husband, but her secret is further threatened when Victor Sarbella, an artist whose brother committed suicide because of Helen, arrives as a guest.
While tensions mount in the household, Don Haskins makes a violent escape from police custody in New York, striking down a detective and stealing a car to reach Greenacres. Pushing his way into the estate, Haskins corners Helen and demands the cash, but she hides him on the third floor when her husband approaches. Shortly after, a shot rings out, and Helen is found dead on the chaise longue in her room with a crimson stain upon her silk robe.
Constable Griggs promptly arrests Victor Sarbella, assuming his motive is Latin revenge for his brother's tragic end. However, a sharp newspaper reporter named Wiggly Price arrives on the scene and begins uncovering critical inconsistencies. Price discovers a cigarette butt and a black hairpin, while Sergeant Tish tracks his stolen pistol to the room, proving that the gun used in the murder belonged to the fugitive crook.
As the investigation unfolds, the cook encounters someone lurking on the third-floor stairway, confirming that Haskins is still hidden in the house. The web of deceit surrounding Helen's past begins to unravel as the authorities realize the suspect list includes not only the vengeful artist, but also a desperate blackmailer and perhaps someone within the family itself.
