The Doctor discovers Castrovalva is a cursive occlusion, an impossible yet manifested Escheresque environment, with all pathways, no matter which direction one goes, leading back to the same point. It is a trap laid by the Master with no apparent way out. Written by
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The script called for Adric to look "pallid", as he was still recovering form the effects of being imprisoned by The Master. Matthew Waterhouse
was extremely hung over after a long night of partying, and ended up having to pause and be sick behind a tree during the scene in which everyone is returning to the TARDIS at the end of the episode. See more
You made us, man of evil, but now we are free!
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