And Then There Were None
S3, E13: One-by-one the female castaways vanish, and when the Professor deduces that headhunters are not to blame, he believes one of the men has become mentally deranged.

S3, E13: One-by-one the female castaways vanish, and when the Professor deduces that headhunters are not to blame, he believes one of the men has become mentally deranged.