A scientist's thoughts materialize as an army of invisible brain-shaped monsters (complete with spinal-cord tails!) who terrorize an American military base in this nightmarish chiller, directed by Arthur Crabtree (Horrors of the Black Museum). This outstanding sci-fi/horror hybrid is a special effects bonanza, and a high-water mark in British genre filmmaking.
Audio commentary: a conversation with executive producer Richard Gordon and genre film writer Tom Weaver
Illustrated essay on British sci-fi/horror filmmaking by film historian Bruce Eder
A collection of trailers from 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 commentary