Betsy Calhoun, a seventeen-year-old runaway from Montana, sits at a hot dog stand in Hollywood, California. Just then, a Chicano gang leader named Feo tells his friend Chucho Valdez that Chucho can erase his $100 debt by helping the gang steal Betsy's suitcase. Chucho chats with Betsy, then pretends to chase the thieves who run off with her belongings. When he returns empty handed, Betsy cries because her money is gone. Chucho invites her to stay at his apartment in East Los Angeles. By the end of the day, Chucho and Betsy go to a dance club and are seen by Feo and his gang. Later, as Chucho and Betsy smoke marijuana, Chucho realizes he is attracted to her and feels guilty about the deception. After Chucho and Betsy have sex and go to sleep, Feo telephones Chucho, telling him to deliver the girl to him. Going outside to confront Feo, Chucho is beaten into semi-consciousness by the gang. The gang enters Chucho’s apartment, gang rape Betsy, and sedate her with a pill. The next day, Betsy’s brother, rancher Jim Calhoun, arrives at the Los Angeles Police Department (LAPD) in his pickup truck. However, Betsy is a juvenile, so the missing-persons bureau considers her only a runaway. Meanwhile, Feo takes the sedated Betsy to Flash, a pimp, and tells him he has a fresh new girl for Johnny Dee. When Flash drives them to Dee’s club on Sunset Strip, Dee turns down their offer because Betsy is drugged, but Barbara, Dee’s girl friend, convinces him to pay Flash $500 for the teenage blonde. Meanwhile, the LAPD’s juvenile division gives Jim a list of halfway houses for runaways, and, eventually, he arrives at social worker Lynn Parsons’ Crisis House. Lynn tells Jim to walk up and down Hollywood Boulevard. Realizing that Jim is as lost as his sister, Lynn agrees to take a few hours off to accompany him there. Across town, Barbara buys Betsy expensive clothes and takes the girl to a luxury apartment. Barbara says Betsy has the looks to be a call girl, but will need intelligence and ambition to be successful. Barbara flips through a fashion magazine, pointing out famous models that began as call girls. As an introduction to the business, Barbara takes Betsy to a party Johnny Dee is throwing that night for high-rolling businessmen. Dee takes them to an expensive hotel, where Barbara gives Betsy $500 before sending her into a hotel room of an awaiting customer. On the boulevard, Lynn separates from Jim so that her contacts will speak with her. As Jim shows Betsy’s photograph to a street cafe’s counter man, three transvestites offer to take him to a man who knows where she is. The transvestites lure Jim into an alley to rob him, but he is large and handy with his fists and sends them running. When Jim rejoins Lynn, she says a man at a magazine stand saw Betsy with Chucho Valdez, a kid from East L.A. The following morning, Jim and Lynn drive to Chucho’s apartment and find him in bed, suffering from his beating. Chucho lies about knowing Betsy, but when Lynn finds a photograph of the girl in the apartment, he confesses that he tried to help her, and that is why he was beaten. He agrees to help find her. When Chucho takes Jim to a bar where Feo hangs out, Jim pummels Feo until he confesses selling Betsy to Johnny Dee. Meanwhile, Barbara takes Betsy to a poker game at Johnny’s penthouse, where Johnny is losing to a high-roller named Curtain. Meanwhile, Jim beats Flash until the pimp gives him the address of Johnny Dee’s office building. At Lynn’s apartment, Lynn and Chucho dissuade Jim from going after Dee, a well-connected vice lord. When Lynn suggests that Dee will surrender Betsy if they impose legal pressure, Jim agrees to wait until the next day. At Dee’s party, Curtain selects Betsy as his date. When Curtain gets Betsy alone, he slaps her, then whips her with a belt, but Betsy cuts him with broken glass. Furious, Curtain pounds her into unconsciousness. Dee spirits Curtain out of the penthouse, promising he will “clean up” the problem. A doctor says Betsy has brain damage and must go to an emergency room, but Dee kills her instead. The next day, Sgt. Miller at the LAPD explains to Jim that the police cannot touch Johnny Dee because they have no evidence. Despite Lynn’s protests, Jim, accompanied by Chucho, drives to Dee’s private office building and smashes his pickup truck through the door. As gunmen surround them, Jim says he is there to talk to Dee. They take him to Dee’s office, where Dee explains that Betsy came to see him, but he sent her away because she was too young. Disbelieving the story, Jim gives Dee the address to Lynn’s Crisis House and says he wants Betsy there in two hours. After Jim leaves, Dee orders Rosey, his bodyguard, to kill him. When Barbara suggests that Dee avoid trouble by turning Betsy over to Jim, Dee confesses that the girl died. Barbara recoils in horror and Dee slaps her with a warning not to tell anyone. At Lynn's halfway house, Jim receives a telephone call that Betsy is in a taxi cab on her way there, but when a taxi arrives, Ben, one of Dee’s gunmen, shoots at Jim from the back seat, but misses. Barbara drives to her apartment to pack a suitcase, but Dee and his henchmen knock her unconscious, put her head in an oven, and kill her. Jim and Chucho drive to Johnny’s apartment building and park in the underground garage. Finding a stepladder, Jim carries it into one of the building’s two elevators, opens the trap door in the roof, and realizes that the other elevator is the only access to Dee’s penthouse. Though Jim manages to get to the top and pry open the door, it sets off alarms, alerting Dee’s henchmen. After a gun battle between elevators, Jim and Chucho run to his pickup truck and drive away. Dee orders his men to comb the barrio for Chucho. When Lynn arrives at Chucho’s apartment to tell Jim that police found Betsy, they go to the morgue so Jim can identify the battered face of his sister. Chucho surrenders to Dee’s henchmen and says he has a proposition for their boss. Upon meeting Dee, Chucho explains that in order to get off Dee’s “hit” list, he will personally kill Jim. In fact, he is supposed to meet Jim in an hour. Dee tells Rosey to drive Chucho to the rendezvous. Rosey gives Chucho a loaded gun, drops him off near Jim’s truck, and watches as Chucho fires several shots into Jim’s back. Chucho jumps back into Rosey’s car, and when they return to Dee’s office, the boss offers Chucho a job in his organization; however, Chucho must go to Mexico for a few weeks to avoid the police. Pleased that Jim has been killed, Dee announces that he is going to Las Vegas, Nevada, for a few days. Chucho returns to Jim, who is still alive because he was wearing a bullet-proof vest. Along with Lynn, they pack road crew equipment into Chucho’s van and drive separately out of Los Angeles. Chucho and Lynn set up a detour sign that diverts Johnny Dee, Rosey, and Ben onto a deserted road. There, Jim blocks their way with his pickup. Rosey and Ben get out of Dee’s car, trying to outflank Jim, but he kills them both. Seeing Chucho’s van pull up behind him, Dee accelerates toward Jim to run him down, but Jim fires a fatal shot through the windshield. As Dee swerves, the car flips over and explodes into flames. Lynn gets out of Chucho’s van and embraces Jim.