| Director | Stuart Rosenberg |
|---|---|
| Genre | film based on a novel, mystery film |
| Runtime | 109 min |
| Country | United States |
| Budget | $2.7 million |
| Box office | $2.6 million |
Lew Harper, a private investigator from Los Angeles, flies to Louisiana to do a job for Iris Devereaux, with whom he'd had a memorable six-day fling, six years earlier. She believes her family's ex-chauffeur, Pat Reavis, is blackmailing her with the knowledge that she cheated on her closeted husband James. James does not care but her tyrannical mother-in-law, Olivia, torments her. Harper is propositioned by Iris's teenaged daughter, Schuyler, and attracts the attention of Police Chief Broussard and Lieutenant Franks. Franks in particular displays a deep-felt personal interest in the Devereaux family.
Oil magnate J. Hugh Kilbourne thinks Harper might be useful in taking ownership of Olivia's oil-rich properties, which she refuses to sell. Harper is abducted by two hoods working for Kilbourne, but Kilbourne releases him after realizing Harper won't help. Olivia has been murdered in the meantime. Harper searches for Reavis, the prime suspect, and is abducted again, this time by hoods working for Kilbourne's wife, Mavis, who demands an account book documenting her husband's illicit dealings.
Harper tracks down Reavis, who denies involvement in the murder of Olivia and the blackmailing of Iris, claiming his presence at Olivia's death was because of an affair with Schuyler. Reavis promises that information he's holding will yield a lot of money for both of them but the car they're riding in is forced off the road by masked gunmen who kill Reavis in a gunfight. Broussard tells Harper no report was made to the police and Franks has been injured in a "hunting accident."
Iris begs Harper to give up the case and he correctly deduces that Reavis gave the account book to his girlfriend Gretchen. Harper ambushes Franks and forces him to admit he works for Kilbourne. Harper then confronts Kilbourne who confesses to hiring Reavis, but only to spy on Olivia, not kill her. Kilbourne offers Harper a fortune for the account book, but Harper refuses. When Franks arrives to visit he is killed by Kilbourne's trained dogs.
Harper is again abducted by Kilbourne, bound and left with Mavis in an abandoned sanitarium. He refuses to turn over the account book and Kilbourne has them tortured before abandoning them in a hydrotherapy room. Harper floods the room, intending to float through the skylight, but the pair are instead trapped in the pool and down to their last breaths when the door opens and Mavis rescues them, killing Kilbourne in the process.
Harper discovers Iris has committed suicide and Broussard reveals they had had an affair seventeen years earlier. Harper confronts Schuyler and lays out how she engineered the entire situation, making her criminally liable. Schuyler insists that "they really did a job on" her father before admitting that she hated both Iris and Olivia. Harper reveals Broussard has been listening to their conversation. Broussard slaps Schuyler but lets her go, confirming he is her real father. Harper visits Gretchen, giving her what's left of Reavis's money, less his expenses, and tells her to send the account book to "the biggest newspaper in New Orleans."