UFO: The Man Who Came Back (Episode 16)

Craig Collins returns after his craft crash-landed in a jungle . Two whole months of his travels are unaccounted for, but he has become much rougher, stronger and sharper, though only Colonel John Grey seems to find any cause for concern and nobody else takes his views seriously. However, when Collins is in Space with Straker it becomes clear that aliens have taken over his mind and Straker has to try and literally talk sense into him.