Private investigator Lew Harper is retained to search for multi-millionaire Ralph Sampson, who has disappeared after flying into Los Angeles.

Sampson's physically disabled wife Elaine wants to ensure her husband is not squandering the fortune she hopes to inherit.

When she passes out, he encounters the armed Dwight Troy, Fay's husband, who falls for Harper's cover story that he is a fan of the former star.

Driving to a remote mountaintop property that Sampson previously had given to Claude, a bogus holy man for his cult's temple, Harper evades attempts to distract him and finds the familiar tire prints.

Harper is caught and questioned by Troy, who knows nothing of the kidnapping or Eddie's part in it but realizes the white convertible belongs to Betty.

When Harper informs Betty that Taggert, her secret lover, is dead, she reveals that Sampson is being held in an abandoned oil tanker.

William Goldman had written the novel Boys and Girls Together (1964), the film rights to which had been optioned by producer Elliot Kastner.

[4] According to Goldman, the script was offered first to Frank Sinatra, who turned it down, then to Paul Newman, who was eager to accept as he had just starred in the period film Lady L (1965), and was keen to do something contemporary.

The name of the lead character was changed from Lew Archer to Harper because the producers had not bought the rights to the series, just to The Moving Target.

"[7] Newman also requested that the character's name be changed from Archer to Harper due to his success in two films beginning with the letter "H"—The Hustler (1961) and Hud (1963).

The job eventually went to Jack Smight, known then for his TV work, who had recently signed a six-picture deal with Warner Bros.

One great thing they had going for them was that the character people were so visually explicit: When Peter Lorre or Sydney Greenstreet walked in on Bogart, you didn't need an explanation.

Filming took place on 23 locations in the Los Angeles area, including Malibu Canyon, Marion Davies' former mansion in Beverly Hills, the Moon Fire Temple in Topanga Canyon, Westwood, Bel Air, Trancas Beach in Malibu, Wrigley Field in Los Angeles, Newhall, San Pedro, Terminal Island, and the Huntington Beach oil fields.

[12] In the title sequence, Newman dunks his head into a sinkful of ice cubes to rouse himself awake, a bit that he repeated in the 1973 film The Sting.

[13] Robert Wagner later recalled Smight "lacked confidence; his wife was with him on the set for the entire shoot and seemed to function as a kind of security blanket.

[18] Newman pulled out of the project, and Sam Peckinpah became attached as director for a while as the film was set up at Commonwealth United Entertainment.