A seductive woman arrives at a ranch party and takes a ride with the rancher. But she's actually Angela, Yvette Mimieux, an assassin, and he is her latest assignment, a minor drug lord. After the kill, she returns home to resume her cover as a professional artist. Her photographer boyfriend Doug Reynolds, Dack Rambo, arrives, yet their reunion is quickly interrupted by an urgent phone call that propels her back into a dangerous world.
The next day, Angela visits the penthouse of Roarke, Clu Gulager, her enigmatic employer. He presses her for one more contract hit, targeting union leader Jeffrey Baine, and she names a price of $125,000 for this final job. The request sets up a tense moral crossroads: money and loyalty clash with a latent desire for a safer life.
Back at Doug's apartment, the couple quarrels over money. Angela hopes to offer financial help to launch Doug's photography career, but he resists, revealing the fragility of their relationship under the strain of her double life. To prepare for the Baine assignment, Angela conducts careful surveillance, studying Baine's routines and weaknesses. She attends a musical recital Baine is at and catches his eye, and he invites her to dinner. They share a dance that stretches late into the night, while Baine's security chief Eddy, Roy Jenson, contemplates a background check on Angela the next morning.
The pair's interactions deepen the perilous web: Roarke and Angela meet again, and she confronts the devastating truth that Roarke will never let her leave this life intact. As Baine grows more charmed by her, Angela revives the seduction strategy to set up the hit, even as Doug calls, hoping for a real future together. When Angela hints she’ll travel, Doug grows suspicious, sensing that something is not right.
Angela and Baine drift toward a lakeside resort after ditching his chauffeur, moving through a sequence of private moments that blur the line between attraction and manipulation. Yet the investigation into Angela's identity intensifies: Baine’s disappearance triggers Eddie’s concerns, and a careful search of Angela's house uncovers multiple passports and a dossier on Baine, exposing the scale of her deception.
A quiet rowboat trip on a calm lake becomes the story’s turning point. Angela pushes Baine overboard; he cannot swim and pleads for help. After a moment of hesitation, she jumps in to rescue him—but in that act, she recognizes she no longer wants to kill him.
Returning home, Angela sees Eddie's car waiting and realizes she cannot escape without Roarke’s protection. She reaches Roarke's penthouse, only to survive an escape attempt that ends with her killing Roarke, the man who bound her fate to this life.
At the airport, she reaches out to Doug and asks him to meet at a Cozumel hotel. What follows is a dreamlike, sunlit interlude that promises freedom, until Doug arrives and the truth crashes in. Angela confesses her true profession, but Doug’s reaction is one of disbelief and shock.
On the beach the next day, Doug reveals a deeper deception: he is another of Roarke's proteges, and Angela is his assignment. She insists Roarke is dead and there is no longer a need to kill her, but Doug refuses to believe it. In a final, fatal confrontation, he shoots her as she attempts to flee and leaves her body to rest on the sand.
