The Stepmother

Returning home late one night from a business trip to Mexico, architect Frank Delgado finds the car of wealthy client Alan Richmond in his driveway. Suspecting that his wife Margo and Richmond are having an affair, Frank attacks Richmond when he steps outside and strangles him to death. Although stunned by his action, Frank drives Richmond's body to the beach and, using a spade he brought from his home, buries the body in the sand. As he finishes the burial, Frank overhears a nearby, young, Latin couple's argument escalate into a fight, but drives away without being seen. The next morning as the police receive a report of the discovery of two bodies at the beach, Frank and Margo are awakened by the arrival of Frank's business partner Dick Hill, his wife Sonya and their friends, pornographic film director Goof and his wife Rita. Although reluctant, the tense Frank agrees to accompany the others to the beach house belonging to Richmond, for whom he and Dick are building another property. At police headquarters, Inspector Darnezi reports to the chief inspector that the bodies of Richmond and a young Latin woman were found near each other on the beach and wonders how they are connected. At the beach house, Dick assures Frank that their business' financial difficulties will soon end as Richmond is due to make a large payment to them that afternoon. Meanwhile, Darnezi investigates Richmond's townhouse and, later, arrives at the beach house. There he informs the group of Richmond's murder, and upon questioning each individual, learns that Richmond had joined all the friends, except Frank, at the Delgado home for an informal party the night before. Suspicious of Frank's terse answers and insistence on the exact time that he arrived home, Darnezi relates his concerns to the chief inspector, who is unconvinced of Frank's involvement. The next day at their office, Dick worries about whether they can secure a loan to cover the large personal investment they made on Richmond's new home. Preparing a barbecue later that afternoon at the Delagdo home, Margo and Sonya discuss their respective marriages and Margo confides in Sonya that Richmond, high on drugs and alcohol, had accosted her the night of his death after everyone else had left the party. Concerned that somehow Frank might know because he has not had sex with her since returning from Mexico, Margo nevertheless asks Sonya not to tell anyone, including Dick. A few days later, Darnezi visits the Richmond construction site to ask Frank and Dick to accompany him to police headquarters to identify Pedro Lopez, who has confessed to murdering his fiancée in a jealous rage on the beach, but insists he has no connection to Richmond's death. Upon leaving the station, Dick announces he will stop by the bank then go to lunch and Frank returns to the construction site. There he runs into Sonya who had hoped to lunch with Dick. Talking Frank into accompanying her, she brings him to a nearby restaurant where Frank is taken aback to see Dick lunching with Margo. Distressed, Frank refuses to remain at the restaurant and, driving back to the construction site, tells Sonya he is not sure he can trust Margo. Tormented by recollections of Richmond's murder and his mounting fear of Darnezi's investigation, Frank goes to the roof of the partially finished building, where Dick finds him sometime later. Enthusiastically relating that they have secured the loan, Dick is stunned when Frank demands to know what he did at lunch. Although he initially denies seeing Margo, Dick then admits that they met at Margo's request because she is concerned about Frank's increasing moody aloofness. Admitting that he knows that Richmond forced himself on Margo, Dick asks Frank to discuss the situation with Margo. Distraught, Frank demands Dick leave him alone and when his friend insists on questioning him, pushes him away only to watch with horror as Dick stumbles and falls off the roof to his death. After Dick's funeral, Frank confesses to his priest, who encourages him to turn himself in. A few weeks pass and, desperate to keep the business going after Dick's death, Frank plans another business trip to Mexico, despite the fact that his college-aged son from his first marriage, Steve, is arriving for a visit. Margo welcomes Steve and, hoping to alleviate his disappointment that Frank is leaving that night, tells him she hopes they can be friends. Later, Frank visits Sonya, who reveals that she intends to put the money from Dick's insurance into the company and asks if she can assume a partnership position and accompany him to Acapulco. Startled, Frank declines her offer. Meanwhile Darnezi has monitored Frank's movements and reports to the chief inspector that Sonya has placed a large amount of money in Frank and Dick's business. That evening Frank has a hasty meal at home before his trip and is unable to communicate with the sullen Steve. Later, Steve overhears Frank and Margo having sex and is distracted and angry. When Frank arrives for his late-night flight, he is surprised to discover Sonya awaiting him. Pointing out that it will look suspicious to the police if they travel together, Frank asks her to reconsider, but Sonya insists she is unconcerned. When Margo telephones Sonya's house, the answering machine message announces that Sonya is in Mexico. Distressed, Margo has several drinks and smokes some marijuana. Hearing Steve playing pool below, she joins him and seduces him. The next morning, the agitated Steve attempts to flee to the family cabin alone, but Margo follows him after a brief argument. The Delgado's housekeeper Lupé, alarmed by Margo and Steve's argument, telephones Frank in Acapulco. That afternoon, Darnezi arrives at the Delgado house with a spade that he shows to the gardener, José, who indicates his initial on the handle, identifying it as his. Darnezi reveals that the spade was found in the trunk of Richmond's car, which was located at the bottom of a lake. That night, Frank arrives back home after cutting his trip short, but is met at the house by Darnezi, who asks him to come to police headquarters. There, Darnezi interrogates Lopez again, hoping to force a confession that he was in league with Frank in the murders. Leaving the station later, Frank drives up to the cabin and upon finding Margo in bed with Steve, goes to his car to retrieve a pistol. Steve hurries out to apologize to his father and Frank confesses that he killed Richmond and is turning himself in. Just then, Darnezi and the police arrive to arrest Frank. When a policeman sees Frank holding the gun, however, he shoots Frank, who collapses on the ground as a distraught Steve rushes to embrace him and Margo looks on in shock.