Air: March 11 1967. 4 eps, all lost.
The crew finds a seemingly happy colony but if anyone mentions that they are seeing strange monsters, they lock them up and wipe their minds. The Doctor finds one man who sees these things and tries to convince everyone, but their mysterious controller has prevented such mention of the word, Macra. The Doctor realizes that this threat has penetrated the very heart of the colony. Can he snap everyone out of this delusion and put an end to this hidden monstrosity?