Hard-living Hollywood starlet Barbara Payton stars as a woman duplicated through technology in this cautionary tale that mixes Home Counties horror with prescient science fiction (Hammer's first). Co-starring Stephen Murray as the unbalanced scientist and directed by Hammer legend Terence Fisher, Four Sided Triangle is featured here as a brand-new 4K restoration from original film elements in its original theatrical aspect ratio.

Lena returns to her home after many years to discover that her two childhood friends Bill and Robin are now scientists and have created a machine that can perfectly duplicate objects. Bill's heart is broken when he realises that Lena loves Robin – until he hits on the mad idea to duplicate Lena in his machine.

Extras:

• Commentary by Melanie Williams and Thirza Wakefield
• with commentary by Kevin Lyons and Jonathan Rigby
• Trailer
• In the Sticks Sci-Fi!
• Terence Fisher featurette TITLE TBC
• I Am Not Ashamed
• Image Gallery