2026 marks the 70th anniversary of this suspenseful science-horror classic from legendary writer Jimmy Sangster. Often considered an unofficial part of the Quatermass franchise, the film makes its debut on Blu-ray and 4K UHD - the latest to be restored by the teams at Hammer and Silver Salt Restoration.

When a soldier dies from apparent radiation poisoning, the Atomic Energy Commission sends scientist Dr. Royston (Oscar-winner Dean Jagger) to investigate. Despite extensive testing no source can be found - until a mysterious radioactive, mud-like entity resurfaces and begins claiming more victims. What do you do when the killer can’t be stopped - or even understood?

This edition comprises:

• Two discs featuring three iterations of the film: the widescreen 1.66:1 UK Theatrical Version, the fullscreen 1.37:1 As-Filmed Version, and the widescreen 1.85:1 US Theatrical Version.
• English, French, Italian, Spanish, German subtitles on all versions of the film.
• Brand-new 5.1 mix for 1.37:1, 1.66:1 and 1.85:1 versions, alongside the original mono film soundtrack.

Discover brand new film commentaries, documentaries, and more. The discs include:

• Making-of documentary about the production of X the Unknown.
• New and archive commentaries with experts that include; Nigel Kneale biographer Andy Murray, film historian David Kalat, writer/producer Dr Steve Haberman.
• Displaced and Damned: A documentary following the career of Joseph Losey - the original X the Unknown director who departed the project before shooting commenced - and his storied journey through Hollywood to Hammer films, via blacklisting and exile.
• An exploration of the groundbreaking work of special effects artist, Les Bowie, including archive audio interviews with fellow special effects technicians and audio from Christopher Lee.
• A Man on the Beach: the rarely seen short film featuring Jimmy Sangster's first scripted work and directed by Joe Losey.
• And more.