The film was based on the 1973 novel of the same name by Dean Koontz, and concerns the imprisonment and forced impregnation of a woman by an artificially intelligent computer.

[4] Gerrit Graham, Berry Kroeger, Lisa Lu and Larry J. Blake also appear in the film, with Robert Vaughn uncredited as the voice of the computer.

Using the basement lab, Proteus begins construction of a robot consisting of many metal triangles, capable of moving and assuming any number of shapes.

Eventually, Proteus reveals its control of the house and traps Susan inside, shuttering windows, locking the doors and cutting off communication.

Using Joshua – a robot consisting of a manipulator arm on a motorized wheelchair – Proteus brings Susan to Harris's basement laboratory.

Gabler is suspicious and later returns; he fends off an attack by Joshua but is crushed and decapitated by a more formidable machine, built by Proteus in the basement and consisting of a modular polyhedron.

[7] Fielding conceived and recorded several pieces electronically, using the musique concrète sound world; some of this music he later reworked symphonically.

[citation needed] Vincent Canby of The New York Times described the film as "gadget-happy American moviemaking at its most ponderously silly," and called Julie Christie "too sensible an actress to be able to look frightened under the circumstances of her imprisonment.

"[8] In the New York Daily News, Rex Reed described Demon Seed as the "kind of insane, self-indulgent, nauseating filmmaking .

"[9] Variety wrote in a positive review, "All involved rate a well done for taking a story fraught with potential misstep and guiding it to a professionally rewarding level of accomplishment.

"[10] Gene Siskel of the Chicago Tribune gave the film one-and-a-half stars out of four, writing that Julie Christie "has no business in junk like 'Demon Seed.

'"[11] Gary Arnold of The Washington Post wrote that director Cammell "plays it dumb on a thematic level, ignoring the sci-fi sexual bondage satire staring him in the face ... What might have become an ingenious parable about the battle of the sexes ends up a dopey celebration of an obstetric abomination.

"[12] Kevin Thomas of the Los Angeles Times called it a "fairly scary science-fiction horror film" that mixed familiar ingredients with "high style, intelligence and an enormous effort toward making Miss Christie's eventual bizarre plight completely credible," though he felt it "cries out for a saving touch of sophisticated wit to leaven its relentless earnestness.

"[2] Lawrence DeVine of The Philadelphia Inquirer wrote that "buried somewhere here may be still more glibness about our technology outstripping our wisdom, and the mechanization of society.

The cynical, however, may have the slightest inkling that a lot of this very expensive-looking sci-fi show business is just to set up a kinky scene with gorgeous Julie Christie spread-eagled at the mercy of a machine that sounds like Robert Vaughan.

"[14] Perry Stewart of the Fort Worth Star-Telegram wrote that "the film’s R rating seems warranted even though there’s no nudity or bad language.

"[16] Clyde Gilmour wrote in the Toronto Star that "the rape and impregnation of Susan Harris by Proteus 4 may defy all logic and offend the pious, but it’s a smashing science-fiction spectacle, impossible to describe.

"[22] Among more recent reviews, Leo Goldsmith of Not Coming to a Theater Near You said Demon Seed was "A combination of Kubrick's 2001: A Space Odyssey and Polanski's Rosemary's Baby, with a dash of Buster Keaton's Electric House thrown in", and Christopher Null of FilmCritic.com said "There's no way you can claim Demon Seed is a classic, or even any good, really, but it's undeniably worth an hour and a half of your time.