X the Unknown 4K Blu-ray Movie

Rating summary

Movie		3.5
Video		4.5
Audio		4.0
Extras		4.0
Overall		4.0

X the Unknown 4K Blu-ray Movie Review

Reviewed by Justin Dekker August 24, 2026

Hot on the heels of the popular and profitable film version of 'The Quatermass Xperiment', Jimmy Sangster was hired to write his first full-length script for another science fiction film which receives its first 4K UDH release in 'X the Unknown 4K' courtesy of Hammer Films. Tightly plotted and supported with inventive effects work, the film stars Dean Jagger ('White Christmas', 'Evil Town'), Edward Chapman ('A Stitch in Time'), Leo McKern ('A Man for All Seasons'), and Hammer mainstay Michael Ripper ('Dracula has Risen From the Grave'). Displaying the impressive results of extensive restoration work, the release includes an expansive assortment of on-disc extras. The film is presented in three aspect ratios, 1.85:1 (US Theatrical), 1.66:1 (UK Theatrical), and 1.37:1 (As-Filmed), in this two-disc set. Blu-ray discs are not included.

Dr. Adam Royston (Dean Jagger) is called in to investigate a mysterious incident that occurred during a military exercise. As the danger grows, it is discovered that the threat is being caused by an entity older than man that periodically emerges from below the earth's surface to feed on radiation. Can the unknowable being be stopped before it's too late?

For lack of a better word, there was a fair amount of controversy surrounding X the Unknown. In the wake of the success of the Quatermass Xperiment, Hammer was keen to capitalize on that success by getting a sequel onto cinema screens as quickly as possible. However, based on how certain elements of the production of that film went, Quatermass writer Nigel Kneale wasn't particularly keen on revisiting the character and his continuing adventures at the time he was approached about the project. Knowing they needed a follow-up, production manager Jimmy Sangster, who had previously adapted a novel for Hammer's short film A Man on the Beach (which is included in this release as an extra), was ultimately tapped to pen a script. The result is a Quatermass-esque picture that inverts certain elements of that highly successful film.

In The Quatermass Xperiment, the film's threat is extraterrestrial, arriving on our planet with the sole survivor of a space journey on a rocket ship that has just returned to earth. In X the Unknown, the danger is already here. Living below the ground is a previously unknown entity whose existence pre-dates that of mankind. The amorphous blob's existence has been previously completely undetectable, and it evidently emerges only to feed after extended intervals. It being the 1950s, the creature's food source could only be radiation, that bugaboo which serves as the direct or indirect menace of many a film from the era.

The nature of the threat and our relationship to it in the films are also polar opposites. The danger is typically kept front and center in The Quatermass Xperiment. Due to Richard Wordsworth's wordless but physically emotional performance, the audience bears witness to his bizarre and terrifying transformation from human to the "other", in gradual and increasingly horrifying steps. While true nature of the danger's physiology isn't known until the film's final frames, the bipedal source of the danger is rarely off-screen for long. A decidedly different choice is made in X the Unknown. In this film, we hear the Geiger counter inexplicably and excitedly clicking, alerting the soldiers and the audience that something is amiss. The ground cracks, subterranean explosions erupt, and soldiers are burned, but the reasons why are unclear. As time wears on, daring children run in fear, an amorous nurse screams in terror, and the number of the dead begins to grow, though the culprit remains mysterious. The threat is established and the tension builds for almost a full hour of the film's 80-minute runtime before the deadly monster makes its first appearance on-screen.

Most importantly in terms of the two films' overall impact, the fundamental nature of the creatures also differ dramatically. Wordsworth's astronaut Victor Carroon is a tragic figure in The Quatermass Xperiment as he plays host to the unknown. After the rocket's inelegant return to our planet, his wife is clearly concerned with his wellbeing. Unsatisfied with what is transpiring at the hospital and simply wanting her husband back regardless of his condition, she arranges for him to be clandestinely removed from the facility and into her waiting car. While his performance had already garnered some sympathy, his loving wife's reaction to him, a mix of shock and revulsion, amplifies that feeling. While clearly unable to stop what is happening to him, he does his best to control himself, clearly not wanting to harm the little girl whom he encounters on the river's edge. That lingering element of his humanity also engenders a certain sense of hope that no matter how slim the odds, something may be able to reverse what is happening before out very eyes. When the transformation is ultimately complete, it's clear that all hope and the Victor Carroon we knew are both utterly lost. X the Unknown has a more straightforward agenda, and terror is the only goal. The menace here is ancient, predating man, or, at the very least recorded history. We're not certain where it originally came from; perhaps the unknowable thing has always been here. Never having the appearance of person, the blobby entity was always foreign since its first moments on-screen. With no factual information with regard to its ecology or society, it is presented as something primal and animalistic by default. It is simply emerging to consume radioactive material before presumably retreating below the the surface for another untold number of years before it needs to eat again. The human victims are merely collateral damage - people in the wrong place at the wrong time. But without either a human form or a doomed human host a sophisticated mix of sympathy, compassion, and horror is never really an option. This creature is simply a frightening and deadly "thing". Regardless, the ultimate decision of how to resolve the situation is the same in both films, and destruction is the only option ever really considered.

Without the more complex emotional and ethical underpinnings of its predecessor, this film's success is the result of more tactical elements. Sangster's script is efficient and effective, adding just the right mixture of character elements and action to propel the movie forward at a consistent and brisk pace. The effects work on display is excellent and inventive, from the simple burns on the soldier and unfortunate child, to the infamous melting head scene, to the movements of the blob-like creature itself. Each generates and escalates the sense of danger. Absent a sympathetic monster, Dean Jagger's Dr. Royston is this film's emotional core. He's a much more believable and empathetic man of science than Brian Donlevy's gruff and brusque Professor Quatermass. With his layered and nuanced performance, we can observe his initial wonder and scientific curiosity. His kindness and compassion allow him to coax information out of the frightened young Ian (Doctor Who's Frazer Hines) so that they may try to save his injured friend. Even his interaction with the tramp in in the tower comes from a place of concern without a hint of judgement or superiority. Without Jagger's performance and these other elements, X the Unknown would not be able to stand beside The Quatermass Xperiment on such relatively equal footing, even despite that film having acquired a superior reputation in the decades since their theatrical releases.

X the Unknown 4K Blu-ray Movie, Video Quality 

Despite an exhaustive search, the original 35mm negative for the film appears to be lost, so a 35mm fine grain housed at Warner Bros in Burbank which had already been scanned at 4K serves as part of the foundation for this release and all associated restoration efforts. A 35mm combined print of the UK version from Hammer's vault was used as the source for the UK titles which were also scanned at 4K. Dirt, defects, scratches and density fluctuations were then addressed, with much of the work done manually. an HDR grade with Dolby Vision was then performed.

The 4K image takes the strengths of the 1080p presentation and expands upon them in two critical areas. First, fine detail is even more elevated, especially in mid-range and close-up shots. Here scientific instrumentation, including various dials and gauges, are clearly rendered, with the cabinets, consoles, or housings that contain them exhibiting appropriate wear and age. Ruin and destruction are most enjoyable. After Royston's lab is inexplicably broken into, the broken glass, the burned elements, and the scarred remains of equipment present every nuanced detail in excellent clarity. So, too, it is with the tower's interior when the professor retraces the ill Will's steps. Stone work displays subtle gradations, the tramp's coat shows dirt and age, and the bottles and cups that line the shelves show every fingerprint, speck of dirt, and the texture of every dent and scratch. The film's miniature shots also provide plenty of detail that is open for inspection. Second, the Dolby Vision grade expands the black and white palette. Blacks are deeper and inkier, adding to the image's depth and dimensionality, with the contents of various shadows and nocturnal scenes being more visible and better defined due to greater gradations of blacks and greys. Whites border on brilliance. The only noteworthy exceptions to the sharp and clear image are process shots where matte paintings are employed to extend or enhance set or location elements. In these instances, the "seams" become visible and there is a certain softness that permeates the shot as is somewhat typical for films of the era. It's not a defect of the transfer, but still worth a mention. It's an absolutely beautiful presentation.

• Screenshots #1 - 12 are sourced from the 1.66:1 UK Theatrical Aspect Ratio.

• Screenshots #13 - 17 are sourced from the 1.37:1 As-Filmed Aspect Ratio.

• Screenshots #18 - 22 are sourced from the 1.85:1 US Theatrical Aspect Ratio.

All screenshots are sourced from the 4K UHD disc and downscaled to 1080 and are in SDR.

X the Unknown 4K Blu-ray Movie, Audio Quality 

As has been the case with many of Hammer's releases, is equipped with two English audio options, an LPCM 2.0 mono track, and, as is Hammer's established protocol, a newly created 5.1 HD-Master Audio track crafted by using AI to strip the dialogue from the mono mixed soundtrack, and pushing music and effects into the surrounds. The 2.0 mono track is the default audio option and is well-done. Dialogue is consistently clean and clear, free from any distortion or sibilance issues. The loudspeaker in the large and cavernous interior of the atomic facility presents with an appropriate echoing quality to sonically describe the size of the space. Effects such as footsteps, crackling Geiger counters, and explosions are era appropriate with well-defined and supported mid-range and upper registers, but thinner low-end support. Music, particularly strings elements, is handled well. Switching to the 5.1 track, the first thing that's noticeable is the theme music swiftly bursting from the surrounds to envelope the listener, however briefly. As soon, as the action of the exercise begins, though, the footsteps and the crackling of the Geiger counter move to the front and park there. Dialogue is normally kept front and center, is clean and clear, and never once betrays its age. Strings are precise, with a better but tasteful bass presence to aid as needed. Explosions are other more powerful sound effects benefit as well, but the assist is never overwhelming or jarring. While it is an interesting alternative to the 2.0 track, it's not quantumly different. To my ear, though, there is a downside to the 5.1 track, which is decidedly front-heavy. Since immersion is infrequent and short-lived, the placement of other sounds and voices behind the viewer is sometimes a bit startling, such as when (at about the nine- minute mark, a distant voice in the lab declares "All finished", suddenly and without context emanating suddenly from the back left and being potted down before the brief line has the chance to finish. Rather than placing the viewer in the lab area, it instead pulls the viewer out of the film. But, such instances are rare. However, all things considered, the 2.0 track is going to be the track I'll select for each subsequent viewing.

X the Unknown 4K Blu-ray Movie, Special Features and Extras 

Hammer outfits X the Unknown 4K with the full compliment of supplemental material.

Disc one

• 2026 Commentary Featuring Toby Hadoke and Andy Murray - Available with the 1.66:1 Theatrical Version, the pair begin with a quick bit of history on Nigel Kneale's The Quatermass Xperiment, and the linkage between that film and this one. The cast dominates the discussion for a time, as due the film's themes and subtexts, and effects. But the ghost of Quatermass returns frequently. Eventually director Joseph Losey and the handoff to Leslie Norman becomes a topic, with the shoot being characterized as "unhappy" overall. Throughout the track, the two work off of each other very well, with many of their remarks feeling spontaneous and conversational. It's an approachable and interesting listen.

• 2026 Commentary Featuring Constantine Nasr and Dr. Steve Haberman - Available on the 1.37:1 As-Filmed Version,

• Into the Unknown (1:.02.51) - In the wake of the success of The Quatermass Xperiment, Jimmy Sangster would be tapped to pen the script for this film, his first for Hammer. Andy Murray (Nigel Kneale's biographer), Toby Hadoke, Richard Klemensen, and others discuss the origins of the project, the making of the film, the censor's reaction, Phil Leaky's effects work, and other subjects. It's an insightful and detailed look at the film's creation.

• A Wide-Awake Dream Merchant (49.13) - Wayne Kinsey, Mike Tilly and others examine Les Bowie's life and his special effects work. The segment begins with his experience during World War II before transitioning to his film career, including his revolutionary work in matte paintings. Time is given to his many contributions to many Hammer films, Kinsey displays pieces of Bowie's work, and portions of an audio interview with Christopher Lee about effects shots he was involved in are also included.

• Jimmy Sangster 2003 Interview (21.35) - In this on-camera interview, Sangster recalls writing his first script at age 27 - X The Unknown - which he states "wasn't a very happy experience". It was a film for which he also served as production manager. He discusses the story's inception, working with Tony Hinds and Michael Carreras, and then moves on to his horror scripts. Taste of Fear and The Nanny also become a subject, and he discusses working with Bette Davis. Sangster talks about working in America and his eventual return to Hammer and directing The Horror of Frankenstein, and he shares some fond memories of Ralph Bates.

Disc Two

• 2026 Commentary With David Kalat - The film historian refers to this film as the "first intentional step forward" for Hammer, as the film's story was cut from new cloth instead of being an adaptation of a radio or stage play. Kalat places this film in historical context landing between the landmark Quatermass Xperiment and the equally important Curse of Frankenstein, before discussing the merits and broader bodies of work of the film's cast, with the long-running original iteration of Doctor Who being a frequent touchstone. Effects work and censorship become a topic, with particular attention paid to the face melting scene. Kalat eventually broadens things out to the broader science fiction and monster movie scene of the 1950s, discussing the common themes and ideas. Eventually, he covers the film's director's history and work. Some of what Kalat has to say is driven by what we see on-screen, but much of it is obviously derived from from comprehensive and factually dense notes. It's a very conversational and informative track.

• 2003 Commentary Featuring Jimmy Sangster and Marcus Hearn - Sangster begins by discussing how be came to be assigned the task of writing the script for this film, before going back and sharing his recollections on his first efforts, including the short film The Man on the Beach. Hearn keeps things moving, asking Sangster about the film's director, his role as production manager, getting into directing, and his screenwriting career. Hearn also probes Sangster about budgets, special effects, rival studios at the time, and the cast. and other topics. With it's interview-like style, it has a tendency to be a bit scattershot, shifting from one topic to another, which is sometimes related to what came before, but at other times this is not the case, and at other times still, questions or comments are based on the on-screen action. Throughout it all, Sangster's recall is voluminous, and is is unafraid to share his opinions. It's a terrific track.

• UK Trailer (1.46)

• Textless UK Tailer (1.47)

• Textless Main Titles (Mute) (1.18)

• UK Censor Card (0.11)

• A Man on the Beach (29.10) - With a screenplay by Jimmy Sangster this crime caper was director Joseph Losey's first work for Hammer, From 1956, the film is tense and briskly paced, and features Hammer mainstay Michael Ripper in a small role. Also available with a commentary from Neill Sinyard.

• Displaced and Damned (1:16.07) - Melanie Williams (Film and Media Historian), John Hamilton (Author and Critic), Gavrik Losey (Producer and son of Joseph Losey), and others discuss this film's original director Joseph Losey's personal history and cinematic works. They share that Losey was a target of the FBI and The House Un-American Activities Committee (HUAC) during the height of the "Red Scare" prompting him to leave the US, and limiting his employability in Britain, his new home. The controversy and last-minute change in this films film's directorship is discussed, before turning their sights to The Damned, his work with David Pinter, and his later works 1960s and 1970s.

• 8mm Cutdown (26.26) - Made for the home-viewing market, this is a condensed version of the film.

• Sidebar: 'X the Unknown' (1:26.29) - Tim Lucas and Stephen R. Bissette, via their traditional split-screen set-up (as first seen on Hammer's Spaceways release, discuss the film by beginning with directing some scrutiny at the film's title, and differences between the "X rating in the US versus the UK. The pair discuss the film's reputation, those who worked on the film, and the numerous films which this picture influenced.

• Restoring the Unknown (11.17) - Hammer's Restoration Manager Mark Stanborough discusses reacquiring the film from Warner Bros., which included a 4K scan of the fine grain. At Silver Salt, Marie Fieldman, (Film Technician) for Silver Salt is on-hand to walk viewers through the restoration process from the moment the cans of film are received to repair work, cleaning, and scanning. Paul Gowlett and Lucas Lehmann (Sr. Restoration Technicians) and Tom Barrett (Sr. Restoration Lead) discuss removing scratches, the dangers of a fully automated process, and resolving noise from the audio track. Senior Colorist Ray King and Mark Stanborough discuss the importance of including the US and UK versions of the film along with multiple aspect ratios, and the more satisfying image that results from broader range of colors in HDR with the deeper blacks and brighter whites. It's a nice peek behind-the-scenes with a bit more information than is typically present in a paragraph or two of restoration notes.

• Image Gallery (15.20) - Posters, lobby cards, stills, and publicity materials auto-advance accompanied by the film's score.

X the Unknown 4K Blu-ray Movie, Overall Score and Recommendation 

Jimmy Sangster's first feature film script, generated quickly to ride the wave of The Quatermass Xperiment's success (even leveraging its naming convention), solidly delivered the goods in a science-fiction/horror hybrid that was a portent of things to come for the prolific writer. Arriving on UK screens slightly over a year after its Kneale-penned progenitor, Sangster's first undeniable success would would be his next film, 1957's The Curse of Frankenstein, a film which put Hammer in the minds of moviegoers on both sides of the Atlantic and set the studio on a path toward horror that would both dominate its output and cement its reputation and legacy. This is, of course, not to take anything away from X the Unknown and the Quatermass films that bookended it. Though not penned by Nigel Kneale, and not sharing any characters including the titular Professor, I feel that this film, along with those two Quatermass films form a more satisfying and cohesive trilogy than the three feature films which actually bear his name (the television films and miniseries are a different animal entirely). Hammer has worked their usual magic here, and the film has never looked or sounded better, and the release is stacked with enough supplemental content to satisfy devout fans and the idly curious alike. For fans of the studio or 1950s science fiction, X the Unknown 4K comes very highly recommended.