Private investigator Lew Harper is pulled away from signing his divorce papers to take on a high-stakes case involving the disappearance of wealthy multi-millionaire Ralph Sampson. His wife, Elaine, who is physically disabled, fears Ralph is squandering her potential inheritance. As Harper delves into his investigation, he meets Allan Taggert, Sampson's private pilot, along with his flirtatious daughter Miranda. A mysterious photograph of a glamorous starlet found in Sampson's bungalow leads him to Fay Estabrook, now an aging alcoholic.
In a risky move, Harper intoxicates Fay to uncover any connection she may have to Ralph's vanishing act. His encounter with Dwight Troy, Fay's armed husband, almost comes to blows, but Harper cleverly disguises himself as a lovesick fan, allowing him to escape. His persistence pays off when he tracks down Betty Fraley, a night lounge singer, but his inquiry about Ralph doesn't go as planned. Betty recognizes Ralph's voice and, in a twist of fate, sends her bouncer Puddler to take care of Harper. Thankfully, Taggert intervenes just in time.
As the investigation intensifies, Harper uncovers that Ralph has left a message for Elaine, urging her to convert $500,000 in bonds. This leads Harper to suspect a kidnapping. On a drive to a remote mountaintop property, he discovers a pot of beans cooking and familiar tire tracks that match those from a previous encounter. A ransom note later found at the Sampson estate adds to the urgency, instructing Elaine to deliver cash that night outside of town.
In a perilous turn of events, the ransom drop goes awry when the man collecting the money is shot, prompting Harper to follow the clues that lead him to The Corner, an unsavory bar where he learns more about the deceased. He soon traces the lifeline back to Puddler, who has escaped detection earlier in the case. The investigation spirals into a smuggling operation masterminded by Troy, and after a chaotic confrontation where Harper narrowly escapes, he begins to piece together the roles of Taggert, Betty, and her brother Eddie in the kidnapping.
After a tense showdown, where Albert Graves, Sampson's attorney, shoots Taggert, Harper rushes to save Betty from the clutches of Troy, Claude, and Fay. He emerges victorious, helps her escape, but in a heartbreaking twist, discovers Sampson's fate is already sealed when they find him dead inside an abandoned oil tanker.
In a final confrontation as they pursue Betty down a hillside, a tragic accident claims her life, leaving Harper and Graves to collect the ransom money as the investigation comes full circle. However, as Harper drives back home, a betrayal of trust reveals that Graves was the mastermind behind the criminal plot. Harper faces a moral dilemma, knowing he must turn Graves in, leading to a tense showdown where the line between right and wrong blurs as they reach his door, with Harper surrendering to his fate.
