It is a dark and stormy night on a rocky and remote planet. An injured alien crawls from a crashed spaceship. A killer (Condo, played by Colin Fay) cuts off the victim’s head and brings it to his Master, who finds it unsuitable and throws it away. The planet Karn is home to the Mystic Sisterhood. They guard the sacred flame which produces the Elixir of Life. Also on the planet is Mehendri Solon (Philip Madoc), a mad scientist who is using the remnants of spacecraft crash victims to create a new body for the living brain of an executed Time Lord criminal named Morbius (Stuart Fell, voice by Michael Spice.)
When the Doctor and Sarah land in the TARDIS, the Doctor knows the Time Lords have done it again and are using him for some purpose. Seeking shelter from the storm, they make their way to Solon’s Citadel. He admires the Doctor’s magnificent head. The Sisterhood are afraid the Doctor has been sent by the Time Lords to steal what remains of their dying flame-elixir. They kidnap him and prepare to burn him at the stake, but he is rescued by Sarah, who loses her sight in the process.
The Doctor is tricked by Solon into believing Sarah’s blindness is permanent and only the Elixir of Life can restore her sight. He asks the Sisterhood for help, learns that Solon is lying, and restores their flame to its former glory. A rampaging brain-damaged Morbius kills Condo, goes in search of the Sisterhood, and kills one of them. The Doctor and Sarah are trapped in the cellar. The Doctor releases cyanogen gas fumes into the ventilation system and Solon is killed, but not before he has completed Morbius’ new body. Morbius accepts the Doctor’s challenge to a mind-bending duel and both are nearly killed in the process. The faces of what are clearly supposed to be the Doctor’s incarnations before William Hartnell appear, but this was unacceptable to fans and later stories corrected the matter. The Sisters, with torches of course, force the insane Morbius over a cliff to his death and use the Elixir to cure the Doctor.
The story was called a superb exploration of Gothic themes—including Frankenstein, H. Rider Haggard’s She, The Island of Doctor Moreau, They Saved Hitler’s Brain, The Old Dark House, The Rocky Horror Picture Show, and Forbidden Planet. Mary Whitehouse of the National Viewers’ and Listener’s Association (self-appointed professional critic of Doctor Who) said it contained some of the sickest and most horrific material seen on children’s television. The BBC tried to get Peter Cushing and Vincent Price to play Solon, to no avail, but Philip Madoc acquitted himself nicely. Karn was stated to be only a few billion miles from Gallifrey, which places it in the same solar system. It’s not surprising to me that the topless towers of Gallifrey should be accompanied by dark trash-worlds and other wretched hives of scum and villainy.