Later that night, Hallson is found murdered in the laboratory's human centrifuge, with the name "Adam Hart" scrawled on a piece of paper in his office.

As the police investigate Hallson's murder, Tanner immediately becomes the prime suspect when it is found that he apparently lied about his distinguished academic credentials.

As Tanner and Lansing search for the other committee members, Melnicker is murdered while Nordlund apparently survives another psychic assault by Hart.

[4][5] The source novel's plot was substantially changed in John Gay's screenplay, moving the location to San Marino, California, changing most of the characters' names (although retaining the surnames of Tanner, Nordlund, and department head Professor Van Zandt), and eliminating several subplots and characters, presumably to fit the film's 108-minute run time.

In September 1964 Pal announced his slate of pictures for MGM were The Power, The Disappearance, Arabian Nights and Odd John.

[10] Hamilton starred as Professor Jim Tanner, with Pleshette as his teammate and romantic interest Margery Lansing (Marge Hanson in the novel), and Michael Rennie (famous among science fiction film fans as Klaatu in The Day the Earth Stood Still) as new government liaison Mr. Nordlund.

[14] This film is memorable for a number of intriguing scenes, including murder by centrifuge, a seemingly possessed "Walk/Don't Walk" pedestrian sign, toy soldiers firing with real gunpowder, and "winking out" inanimate objects (the last two also in the novel).

The soundtrack also memorably features a beating heart to signal the mind-control attempts and eerie music from a cymbalum (a hammered dulcimer-like instrument) accompanying the film's more suspenseful moments.

The music, written by Oscar-winning composer Miklós Rózsa, contributes an amusing fourth wall-breaking moment when Tanner, hearing the haunting tune, seems to expect a new disaster, only to be visibly relieved when he finds a cymbalum-violin duet being performed in the hotel lobby.