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What is Encounters with the Third Doctor for The Master in Doctor Who?
The Master, played by Roger Delgado, makes his first appearance in Terror of the Autons (1971), where he allies with the Nestene Consciousness to help them invade Earth.
Who encounters the Third Doctor in Terror of the Autons in Doctor Who?
The Master
Who is The Master in Doctor Who?
The Master is a recurring character in the British science fiction television series Doctor Who and its associated spin-off works.
Is there anything interesting about the Doctor Who The Master article?
In The Sea Devils (1972), the Master is shown to be imprisoned on an island prison off the coast of England.

Question: Why is he imprisoned?
Self-contained rewrite: Why is The Master imprisoned in Doctor Who's In The Sea Devils?