DVD FEATURES:
Cast List:
Tom Baker - The Fourth Doctor (eps. 75-116)
Peter Davison - The Fifth Doctor (eps. 117-136)

Matthew Waterhouse - Adric (eps. 112-122)
Sarah Sutton - Nyssa (eps. 115-127)
Janet Fielding - Tegan Jovanka (eps. 116-134)

Geoffrey Beevers - Melkur
 - Geoffrey Beevers played The Master but was credited as the Melkur to conceal this plot twist.

Anthony Ainley - Neil Toynay
 - 'Neil Toynay' is an anagram of 'Tony Ainley'. The pseudonym was used in order to conceal the
    plot twist as he was actually The Master.

#114 The Keeper of Traken, 4 parts:
The planet Traken. The Traken union is a society living in perfect harmony, watched over by the powerful but benign Keeper. But now the Keeper is dying, and he senses a great evil within his protectorate. Can the Doctor help him discover the secret of the Melkur?

The Doctor and Adric learn from the wizened Keeper of Traken that a great evil has come to his planet in the form of a Melkur - a calcified statue. The Keeper is nearing the end of his reign and seeks the Doctor's help in preventing the evil from taking control of the bioelectronic Source that is the keystone of the Traken Union's civilisation.

The Melkur, via various deceptions, becomes the next Keeper. It is then, however, revealed to be the Master's TARDIS. Its owner, still blackened and emaciated, hopes to use the Source's power to regenerate himself. The Doctor manages to expel him and install a new Keeper in his place, but in a last minute ploy the Master traps one of the Traken Consuls, Tremas, and merges with his body before fleeing the planet.

First appearance of Sarah Sutton as Nyssa of Traken, although she doesn't actually join the TARDIS crew until Logopolis.

#115 Logopolis, 4 parts:
Southern England, 1981. Air hostess Tegan's first day on the job does not go as planned when she pulls over by a police box with a flat tyre en route to the airport. Why is the Doctor suddenly interested in genuine police boxes? And what is the terrible secret of the planet Logopolis?

The Master is up to his old tricks and shrinks Tegan's auntie and a policeman to death.

Then the Master accidentally causes the universe to collapse by destroying Logopolis, the civilisation that was holding it together.

The Doctor and the Master form a hurried plan to try and prevent the universe falling apart, but the Master is quick to turn the situation to his advantage and hold the universe to ransom.

Sarah Sutton (Nyssa of Traken) does not appear in this episode.

First appearance of Janet Fielding as Tegan Jovanka

#116 Castrovalva, 4 parts:
Southern England, 1981. The universe has been saved, but at the cost of the fourth Doctor's life. The newly-regenerated fifth Doctor must rely on his friends to survive as the regeneration threatens to fail. But an old enemy is still lurking and has one trap after another to lure the TARDIS crew into...

With the Doctor recovering from a difficult regeneration, his companions take him to the tranquil planet of Castrovalva.

What they don't realise is that the whole society is a trap created by the Master, who has disguised himself as the kindly Portreve.

As the trap begins to close in, so the whole town begins to collapse, becoming an unstable area of space time.

With the walls literally closing in, the Doctor and his companions manage to escape - but the Master isn't so lucky, and is torn apart by his own creations .... or is he?

First full appearance Peter Davison as the Doctor
 

Castrovalva
The title of this story comes from a print by renowned Dutch artist M.C. Escher who was much celebrated for his use of impossible perspectives and optical illusions. The full significance of this allusion becomes clear in episodes three and four when the collapsing world of Castorvalva takes on a distorted appearance reminiscent of Escher's work.