The screenplay by Herbert J. Leder was based upon Amelia Reynolds Long's 1930 short story "The Thought Monster", originally published in the March 1930 issue of Weird Tales magazine.
U. S. Air Force Interceptor Command Experimental Station No. 6 is a long-range radar installation located in Winthrop, Manitoba, Canada. Unexplained deaths begin to occur in the general area of a farming village near the American base. Postmortems reveal the victims were murdered and the brains and spinal cords are missing from the corpses; the only clue left behind are two puncture marks at the base of each skull. The locals, however, become convinced that radiation leaks from the radar installation's nuclear-power experiments are the cause of the mysterious deaths.
Air Force Major Jeff Cummings (Thompson) begins an investigation as the local deaths continue, interviewing various townsfolk, while looking for anything unusual. Cummings becomes suspicious of Professor R. E. Walgate (Reeves), a retired British scientist living near the airbase; Walgate is in the process of writing another book about his ongoing experiments with telekinesis, this time as it applies to thought projection. Major Cummings' suspicion of Walgate is later proved to be correct. The scientist finally admits he has not only succeeded in developing his mental ability, but in the process created a living thought projection. Unknown to Professor Walgate, the nuclear power radar experiments underway at the nearby U. S. airbase have greatly enhanced his mental abilities to the point that, through him, his living thought projection has become a malevolent and invisible new life form. It escaped from Walgate's laboratory and is now attacking humans as a means of replicating physical, though still invisible, new versions of itself, all of which are now feeding on the base's nuclear-generated power.
The invisible creatures eventually attack and kill the military personnel at the airbase in order to take over control of the radar station's nuclear reactor; two of them dial-up the power to very dangerous levels. As they do so all the creatures suddenly become visible. Their now visible bodies are revealed to be the missing brains with spinal cords stolen from their victims; their spinal cords have become very flexible and have now sprouted tendrils. These mutations also allow the brain-spine creatures to move quickly and even leap distances; each brain-spine has also developed a pair of small eyes at the ends of extended eye stalks.
The slithering creations then attack Walgate's home, where most of the film's principal characters have gathered to discuss the crisis. Some of the brains get inside by breaking through a boarded-up window using their tendrils, while others leap to the roof and slither down through the fireplace's open flue. Some of the defenders are attacked and killed, but well-aimed .45 semi-automatic pistol shots to the brains soon make short work of most of the attacking creatures; they gorily bleed out as they expire. Professor Walgate exits his home as a diversion, but is quickly attacked and killed by his creation. Meanwhile, Major Cummings escapes out the back way and quickly heads to the airbase, where he saves the day by blowing up the radar installation's power machinery. This immediately robs the surviving brains of their high-energy food source, and the creatures quickly die, dissolving into puddles of goo.
Noted science fiction personality, collector and literary agent Forrest J Ackerman represented mystery and science fiction pulp writer Long and brokered the sale of her story "The Thought Monster" to the film's producers.
Screenwriter Leder was originally set to direct the film, but being American, was unable to obtain a British work permit in time, so Crabtree replaced him as director. Thompson later said that when the director showed up on the first day of shooting and looked at the script, Crabtree claimed it was not the film he had been hired to direct as he did not do "monster" films. After a heated argument with the producers, Crabtree left the set and did not show up for several days. In the interim, Thompson himself directed the film.
Fiend Without a Face was made entirely in England. Its Canadian setting was chosen because it would appeal to both American and British Commonwealth movie audiences, while still being easy to replicate using the English shooting locations. U. S. Air Force stock aviation footage was also used to establish the military base setting and to pad out the film's meager running time. The producers used primarily expatriate American and Canadian actors working in the United Kingdom, plus a few British actors dubbed by Americans.
The film's visible brain creatures were created using stop-motion animation, an unusual practice for such a low-budget science fiction thriller of this era. The director of these effects sequences was Florenz Von Nordoff, while the actual stop-motion was done in Munich by Nordhoff's partner, German special effects artist K. L. Ruppel. Peter Neilson headed up the British practical effects crew.
During July 1958, Fiend Without a Face first opened in the United States at the Rialto Theatre in New York City's Theater District. The film's producers placed an outdoor, front-of-the-house exhibit near the sidewalk that showcased a "living and breathing Fiend" in a steel-barred glass display case. It periodically moved its spinal cord tail, startling onlookers, and also made menacing sounds with the help of a concealed electrical device. The crowds that gathered to watch the caged Fiend grew so large that NYC police finally ordered the display case removed because it was creating a public disturbance.
Five months later, Fiend Without a Face created a public uproar after its British premiere at the Ritz Theatre in Leicester Square in London's West End. The British Board of Film Censors had demanded a number of cuts before its release and finally granted the film an "X" certificate, but newspaper critics were still aghast at its horrifying special effects. Questions were actually raised in Parliament as to why British censors had allowed Fiend Without a Face to be released, notably: "What is the British film industry thinking by trying to beat Hollywood at its own game of overdosing on blood and gore".
With a 67% "Fresh" rating at the review aggregator website Rotten Tomatoes, Fiend Without a Face is considered one of the best B movies of the 1950s. James Rolfe called the film the best killer brain movie ever and stated that "it may be the goriest film of its time". Later reviews concentrated on the B-movie production values and lack of a cohesive plot. In Leonard Maltin's review, he noted, "...horrific climax, good special effects."
According to MGM records, Fiend Without a Face was released on a double feature with The Haunted Strangler; together, they earned $350,000 in the U. S. and Canada and $300,000 in England and elsewhere. As the film's estimate budget was £50,000, this resulted in a profit of $160,000.
On 22 March 2010, Roy Frumkes confirmed to Fangoria magazine that he would produce a remake of the film in 2011.
The online website Dread Central offered an October 2013 update from Frumkes on his Fiend Without a Face remake:
"I've wanted to do this film for 40 years, so I already had it all in my head, and it wasn't hard to write. What I didn’t have was the technical information; I'm no science buff. Now I’m interviewing scientists, getting the technology straight. It's set in a think tank in the Berkshires, and it's not about young people. It's a mature film, but it has a Street Trash sensibility, so the people who like my work will not be disappointed".
The website also posted a still from a fundraising trailer that Frumkes had shot for the remake with director Franco Frassetti.
Montreal-based filmmaker Rémi Fréchette produced, co-wrote and directed a web series (2013) and a feature film (2014) called Les Jaunes, in close resonance with the themes and images of Fiend Without a Face, including its military aspects, rural setting and energy-based brain creatures.
The Criterion Collection, a video company known for its painstaking restorations of various film classics, released a deluxe DVD edition of Fiend Without a Face in 2007, having previously released it on LaserDisc.
A high-definition video transfer, created on a Spirit DataCine from a 35 mm film print, was struck from the film's original negative. Thousands of pieces of dirt, debris and scratches were removed using the MTI Digital Restoration System. For optimal image quality, Criterion also encoded the dual-layer DVD-9 at the highest possible bit rate. The film's original monaural soundtrack was remastered at 24-bit, and audio restoration tools were used to eliminate clicks, pops, hisses and crackles.
Criterion added these bonus DVD features to their release:A new widescreen 1.66: 1 transfer with a complete digital picture restoration enhanced for 16×9 hi-def televisions.
Audio commentary: A conversation with executive producer Gordon and genre film writer Tom Weaver.
An illustrated essay on British science fiction/horror film making by film historian Bruce Eder.
A collection of movie trailers from various Gordon films: Fiend without a Face, The Haunted Strangler, Corridors of Blood, First Man into Space and The Atomic Submarine.
Rare still photographs and ephemera, with audio commentary.
Vintage advertisements and lobby cards.
New English subtitles for the deaf and hearing impaired.
A new DVD cover art design by David Cohen.