Alex awakens, packs his belongings into two bags, gathers photos of him firing a gun with a woman, and leaves as the woman sleeps. Outside, he tosses one of the bags into the back of a trash truck. Meanwhile Michael Boll, a stressed-out trade analyst at a securities company on Wilshire Boulevard in Los Angeles, California, complains to his coworker, Patterson, that somebody has removed the material for his upcoming presentation from the company computer system, and only three other people had access to it. When Michael’s fiancée, Ruth Fielding, arrives at his office to talk about changing their wedding date, he suffers stomach cramps. Later, Michael drinks beer at a bar in Manhattan Beach, California. After he buys a young woman a drink, her boyfriend, Willie, storms in, and tells Michael to get lost. When Michael objects, Willie slams his head against the bar. Suddenly, Alex appears and scares Willie away with a broken bottle, but before Michael can thank him, Alex disappears. Going home, Michael realizes his wallet is missing. Frank “Pismo” Boll, Michael’s older brother, comes to his apartment to borrow money. He complains that nobody will hire him because of his time in prison, but Michael blames Frank's unemployment on his marijuana habit. During an evening run, he sees Alex and offers to buy him a drink. Michael complains about his job, and Alex suggests that Patterson, his co-worker, is sabotaging him, and challenges Michael to beat Patterson at his own game. Alex takes Michael to a trendy nightclub and encourages him to talk to two attractive women. The two ignore Michael, but one of them, Claire, warms to Alex and dances with him. Feeling out of his league, Michael leaves. At work, he enters baseball statistics into Patterson’s “section report.” Later, after telephoning Ruth to tell her that he cannot accompany her to her parents’ home that evening, Michael returns to the nightclub and discovers that Alex, known to everyone there as “Tony,” lives upstairs. When Alex takes Michael to an art gallery opening, he introduces himself to several well-heeled patrons as “Maxwell Cunningham,” but when he sees Claire, he speaks with a French accent, whispers to Michael to call him “Franco,” and introduces Michael as “Dominic,” whose wife recently passed away. The three go back to Michael’s apartment, where Alex convinces Claire to go to bed with Michael, whom he now calls “Mick.” However, Michael later discovers that Alex videotaped them making love. When Michael reveals his indifference toward Ruth and his desire to get a promotion over Patterson to senior analyst, Alex tells him to “make it happen.” At lunch at the La Brea Tar Pits, across the street from his office, Michael tells Alex he could make a killing in the stock market if he sells just before closing, but if the next day’s figures are down, his decision would be a disaster. At Alex’s suggestion to take a chance, Michael sells, and the next morning he makes a huge profit for the company. Imbued with confidence, he tells his secretary, Leslie, to call him Mick. That night, he accompanies Ruth to a party at her parents’ estate and is surprised to find Alex there, portraying a Frenchman named “François” from the “Paris office” of Michael’s company. Alex leads everyone into the family den and plays the videotape of Michael having sex with Claire. Ruth becomes hysterical, and her father chases Michael from the house. As Alex hurries him away, he declares that Michael’s problem with his fiancée is solved. They drive to a party, where Claire greets Michael warmly. He admits that his real name is “Kirk,” not “Dominic,” and he does not have a dead wife. After Michael gets high on cocaine and liquor, Alex takes him to a hamburger stand, puts a fake gun to the clerk’s head, and orders the compliant Michael to rob the cash register. As they drive away, Michael realizes what happened and becomes sick, but when Alex stops at a liquor store and robs it too, Michael more willingly participates. Afterward, he tells Alex they are in Patterson’s neighborhood. The next morning, they awaken in Michael’s apartment with a pile of money, and Michael notices scrapes on his knuckles. At work, Michael hears that Patterson was badly beaten last night. Later, Michael orders Alex out of his apartment, but as Alex leaves, he says, “You got what you wanted.” The next day, Michael’s boss, Howard, tells him that Patterson withdrew from competition for the senior analyst job. Returning home, Michael finds his furniture gone. At the nightclub, Alex confesses he took it as payment for getting Michael his promotion, and Michael declares them “even.” He goes to brother Pismo’s rundown apartment and spends the night. At the office, the battered Patterson avoids him. Alex telephones to say he sold Michael’s furniture, but still has his photos, computer discs, passport, and the lost wallet, all which can be found in a box near Well #43 in the Baldwin Hills oil fields off La Cienega Boulevard. Michael drives to the well and gets the box. Returning to his apartment, he finds his television there, along with a video camera and a cassette, ready to play. On the videotape: Alex says Michael “asked for this.” There is a knock on the door, and Claire enters, asking for Michael. Alex takes her into Michael’s room, and screams are heard. Running into the bedroom, Michael finds Claire’s bloody body. He returns to the camera, but Alex appears, knocks him down, and takes the videotape on his way out. Later, Michael explains his dilemma to Pismo, who agrees he cannot go to the police. They wrap Claire’s body in a curtain, take an elevator down to the garage, and break into the La Brea Tar Pits to hide her in the dark, oily water. The next day, as he looks out his office window, Michael sees an ambulance arrive at the tar pits. Running over, he watches workers pull Claire’s body from the murk, then sees Alex nearby, watching. Realizing that Alex saw them dump the body, Pismo fears he will be sent back to prison. They devise a plan to get Alex’s fingerprints in order to discover his real identity. Using underground newspaper advertisements for the type of “fun-loving couples” parties Alex regularly attends, Michael sends Pismo to find him. Spotting Alex at a club, Pismo waits until he goes to the bathroom, then steals his beer bottle and glimpses Alex’s driver’s license, with a Manhattan Beach address. However, Alex sees Pismo leaving, and follows. Meanwhile, Michael borrows a pistol from Rito, a guard at his office building, claiming he must protect his company’s $40,000 over the weekend until the Monday deposit. When Pismo arrives home, Alex chases him onto a fire escape, but runs away as Michael arrives. Michael hurries upstairs, but when he returns to his car, he finds that Alex has smashed a tail light and hooked it up to a wire in his gas tank, set to explode when he puts on the brake. Michael drives to the Manhattan Beach address on Alex’s driver’s license and finds him in bed with two women. Michael confronts him, then escapes and lures Alex to a nearby pier. As Alex catches him, Michael pulls Rito’s gun. Alex confesses he beat Patterson when Michael was passed out, then scraped Michael’s knuckles on the pavement. He also admits he killed Claire to show Michael that he, like most people, was a hypocrite feigning innocence. Suddenly, Pismo appears with a videotape camera, saying he recorded every word. Alex lunges, Michael fires the gun, blowing Alex into the water. Pismo calls police. As police cars approach, Michael goes to tell them what happened.