Parts: 4
Writer: Robin Bland (aka Terrance Dicks and Robert Holmes)
Airdates: 3 January 1976 - 24 January 1976
Production Code: 4K

Doctor: fourth
Companion: Sarah

Megalomaniac of the Week: Morbius

Story: On the desolate, stormy planet of Karn, a dazed insect struggles away from the wreck of its craft...and is promptly killed and beheaded by a lurking man with a hook for a left arm. This is Condo, manservant to the once-famous neurosurgeon Mehendri Solon, who lives in a castle on the planet. The Doctor arrives on Karn soon afterward, suspicious that the Time Lords have yet again influenced his landing. Sarah finds a massive spaceship graveyard on the planet, but another storm breaks, causing them to seek refuge in Solon's castle.

Also on Karn is a group known as the Sisterhood, who have survived for hundreds of years using their Elixir of Life. The Elixir is made by the Sisterhood's Sacred Flame - but the Flame has been running low for months, and the Sisterhood is threatened with extinction. When they learn that the Doctor has come to Karn, they suspect that he has come to steal the last of their Elixir - and being a Time Lord, the only other beings equal to the Sisterhood in power, they fear there is little they can do to stop him...but they are certainly going to try.

The Doctor and Sarah begin to suspect that Solon's castle was not the wisest choice of refuge. Solon himself seems to be fixated on the Doctor's head; the Doctor finds a stone bust of Morbius, a notorious Time Lord criminal; and then their wine is drugged. Sarah, having chosen not to imbibe, feigns unconsciousness as Solon makes his plans for the Doctor's body...plans which center around removing his head. Pieces to the horrible puzzle begin to fall into place when Sarah comes across a brain without a body. Solon intends to revive Morbius...and once he has the Doctor's head, his mission will be practically accomplished...