After closing his New York City private detective agency due to a lack of business, William H. Reardon goes back to work for the district attorney's office. The office does not stay closed for long, however, as Bill's vivacious wife Sally has decided to reopen the debt-ridden agency and run it herself. The agency is soon headed for success when rich socialite Lola Fraser commissions Sally to follow her husband Walter, whom she suspects of having an affair with Anne Calhoun, his former sweetheart. Later, Sally persuades Bill to take her to the expensive Skyline Club, where, unknown to Bill, she spies on Lola, Walter and Anne, and makes a spectacle of herself in the process. Sally's interest is piqued when she sees Walter pass a note to Anne, who then gives it to the nightclub's owner, Nick Shane. Sally then witnesses Jerry Marlowe, Anne's fiancé, become jealous of Walter and threaten to kill him. The following day, newspaper headlines report that Walter has been murdered. Because Sally has provided the police with a tip that Jerry may be the killer, Jerry's attorney, Mr. Ketterling, hires her to prove his client's innocence. Sally eavesdrops as Bill, who has also taken up the investigation, questions the suspects in the Fraser home. She later discovers Anne in Lola's apartment trying to steal an incriminating letter that she had written to Walter. On another occasion, Sally goes to Lola's apartment, where Shane, who has just demanded $50,000 from Lola, hides. When Sally returns home, she finds Shane's body and smells the fragrance of Lola's perfume. The clues eventually lead Sally and Bill to the conclusion that Lola is the killer, and they trick her into confessing to her husband's murder. It is then learned that she killed her husband because she learned from his attorney that he was planning to divorce her. Realizing that she would be wealthier as a widow, Lola hired Shane to kill Walter, but when Shane tried to blackmail her, she killed him. With the case solved, Bill and Sally rush back into each other's arms.