The Brain of Morbius is the fifth serial of the 13th season of the British science fiction television series Doctor Who, which was first broadcast in four weekly parts on BBC1 from 3 to 24 January 1976. The screenwriter credit is given to Robin Bland, a pseudonym for writer and former script editor Terrance Dicks, whose original script had been heavily rewritten by his successor as script editor, Robert Holmes. It is the first serial to feature the Sisterhood of Karn.
The serial is considered to have many thematic links to Mary Shelley's novel Frankenstein. It is set on the planet Karn, where the surgeon Mehendri Solon (Philip Madoc) seeks to create a body for the Time Lord war criminal Morbius (Stuart Fell and Michael Spice) from parts of other creatures that have come to the planet.
Plot
On the planet Karn, an insect-like alien is killed by Condo who takes its head to a castle and his master Solon. However, the head is unsuitable — Solon needs a head from a warm-blooded humanoid.
The TARDIS materialises and the Fourth Doctor rushes out, the Time Lords having diverted him to this planet. Sarah Jane Smith finds a valley filled with wrecked spacecraft, as well as the headless body of the alien which is identified as a Mutt. She and the Doctor make for the castle that she spots. The travellers are welcomed by Solon who compliments the Doctor on his "magnificent" head.
Meanwhile, the Sisterhood of Karn discover the TARDIS and teleport it to their temple. Their elderly leader, Maren, identifies it as a Time Lord vessel, and believes that the Doctor has come to steal their Elixir of Life.
The Doctor knows of Solon as an authority on microsurgical techniques and tissue transplant. The Doctor recognises a clay bust as that of Morbius, one of the Time Lords' greatest criminals. Before he can say anything further, a drug takes effect, and the Doctor passes out. Sarah Jane pretends that she has succumbed. In the laboratory, Solon's examination of the Doctor confirms that he is a Time Lord. As he and Condo leave the room, the Doctor vanishes. Sarah Jane keeps hidden and enters the lab. She draws back the curtain on a bed, thinking it is the Doctor, but as the lights come up, she sees a headless, patchwork creature made from various body parts.
The Doctor regains consciousness to find himself surrounded by members of the Sisterhood. The Doctor realises that just before he passed out, he felt the mind of Morbius. Maren refuses to believe him.
Sarah Jane follows Solon and Condo as they make their way towards the temple. Solon asks the Sisters to spare the Doctor, or at least give him the Doctor's head. A disguised Sarah frees the Doctor, but she is blinded by the energy from Maren's ring. They return to the castle, where the Doctor asks Solon to examine Sarah Jane's eyes. Solon tells him that Sarah's retinas have been almost completely destroyed, but there is one chance: the Elixir of Life. The Doctor goes to the Sisterhood, unaware that Solon has lied about Sarah Jane's condition and has notified the Sisterhood that the Doctor is coming back.
Sarah Jane hears a voice calling for Solon. Following the sound, she enters a hidden laboratory and stumbles blindly towards a glowing brain in a tank, which accuses her of being sent by the Sisterhood to destroy it. Solon enters and drags her away. As he closes the door, she hears Solon address the voice as "Morbius" and hears how Solon has sent the Doctor into a trap. She locks Solon in the laboratory and, still blind, makes her way out of the castle.
The Doctor is captured by the Sisterhood. When he explains why he came back, Maren tells him that the ray's effect is not permanent, and Solon knows that. The Doctor believes that something evil related to Morbius is happening. Maren affirms that she saw Morbius dispersed. The Doctor asks if Solon was present. Morbius had led an army of mercenaries, promising them the Elixir and immortality and revealing its existence to the cosmos. The Doctor reignites the flame with a "Little Demon."