A boxed set containing three stories telling the tales of the TARDIS' marooning in the universe of E-Space...
 

Serial: 5R  Episode Nos. 540, 541, 542, and 543.  Title: Full Circle

After passsing through a spatial disruption, the TARDIS lands on a planet that the scanner says is Gallifrey.  It is in reality
Alzarius, a world entering a dangerous time known as Mistfall to the people living there from the nearby crashed Starliner.
When Mistfall comes, creatures leave the swamps and attack those from the Starliner, and they now include the Doctor and
Romana in their rampage of chaos...

This story sees the debut of Matthew Waterhouse as Adric.

starring Tom Baker as Doctor Who, Lalla Ward as Romana, Matthew Waterhouse as Adric, and John Leeson as the Voice of K9. Written by Andrew Smith, Executive Produced by Barry Letts, Produced by John Nathan-Turner, and Directed by Peter Grimwade.

Originally transmitted from 25 October 1980 to 15 November 1980 on BBC1.
 
 

Serial: 5P  Episode Nos. 544, 545, 546, and 547.  Title: State of Decay

Searching for a way out of E-Space, the Doctor lands the TARDIS on a planet with but one village near a fortress-like
Tower.  In the Tower live the Three Who Rule, oppressive Lords over all the villagers who grind them to the limit to serve
a greater master who has given the Lords the eternal life that of vampirism.  Now the Great One is ready to
awaken after a thousand years of slumber, and only the Doctor can stop it from once again terrorizing the entire universe.

starring Tom Baker as Doctor Who, Lalla Ward as Romana, Matthew Waterhouse as Adric, and John Leeson as the Voice of K9. Written by Terrance Dicks, Executive Produced by Barry Letts, Produced by John Nathan-Turner, and Directed by Peter Moffatt.

Originally transmitted from 22 November 1980 to 13 December 1980 on BBC1.

Serial: 5S  Episode Nos. 548, 549, 550, and 551.  Title: Warriors' Gate

There is a place that is nowhere, where the Time Winds blow, where universes of time and space meet.... it is called the
Gateway.  It is in this place where a ship with a human crew and lion-like time-sensitive slaves called Tharils has become
marooned between the time lines.  A Tharil called Biroc escapes and hijacks the TARDIS here too, leading the Doctor
towards the way out of E-Space, and, he hopes, his people toward freedom....

This story sees the departure of Lalla Ward as Romana and John Leeson as the Voice of K9.

starring Tom Baker as Doctor Who, Lalla Ward as Romana, Matthew Waterhouse as Adric, and John Leeson as the Voice of K9. Written by Steve Gallagher, Executive Produced by Barry Letts, Produced by John Nathan-Turner, and Directed by Paul Joyce.

Originally transmitted from 3 January 1981 to 24 January 1981 on BBC1.