Private detective and former football player Harry Moseby gets hired on to what seems a standard missing person case, as a former Hollywood actress whose only major roles came thanks to being married to a studio mogul wants Moseby to find and return her daughter. Harry travels to Florida to find her, but he begins to see a connection between the runaway girl, the world of Hollywood stuntmen, and a suspicious mechanic when an unsolved murder comes to light.
Harry Moseby (Gene Hackman) is a retired professional football player now working as a private investigator in Los Angeles. He discovers that his wife Ellen (Susan Clark) is having an affair with a man named Marty Heller (Harris Yulin).
Aging actress Arlene Iverson (Janet Ward) hires Harry to find her 16-year-old daughter Delly Grastner (Melanie Griffith). Arlene’s only source of income is her daughter’s trust fund, but it requires Delly to be living with her. Arlene gives Harry the name of one of Delly’s friends in Los Angeles, a mechanic called Quentin (James Woods). Quentin tells Harry that he last saw Delly at a New Mexico film location, where she started flirting with one of Arlene’s old flames, stuntman Marv Ellman (Anthony Costello). Harry realizes that the injuries to Quentin’s face are from fighting the stuntman and sympathizes with his bitterness towards Delly. He travels to the film location and talks to Marv and stunt coordinator, Joey Ziegler (Edward Binns). Before returning to Los Angeles, Harry is surprised to see Quentin working on Marv’s stunt plane.
Harry suspects that Delly may be trying to seduce her mother’s ex-lovers and travels to the Florida Keys, where her stepfather Tom Iverson (John Crawford) lives. In Florida, Harry finds Delly staying with Tom and a woman named Paula (Jennifer Warren). Harry, Paula, and Delly take a boat trip to go swimming, but Delly becomes distraught when she finds the submerged wreckage of a small plane with the decomposing body of the pilot inside. Paula marks the spot with a buoy, and when they return to shore, she appears to report the find to the Coast Guard.
Harry persuades Delly to return to her mother in California. After he drops her off at her California home, he still is uneasy about the case, but focuses on patching up his own marriage. He tells his wife he will give up the agency, something she has wanted him to do for a long time, but then he learns that Delly has been killed in a car accident on the set of a movie….