Starring Terence Stamp, this film revolves around a socially inept butterfly collector named Freddie (played by Stamp), who out of a perverse desire for companionship, decides to begin collecting women as well. When Stamp notices Samantha Eggar's character, a beautiful well adjusted stronger woman, he decides she would make an excellent companion, kidnaps her and imprisons her in his basement.
I think what I like most about this story is the way Stamp's character rationalizes his actions and treats his victim like she's acting foolish in not wanting him to have a companion. This strange tone is continued throughout, until the surprising conclusion. It's like a morality tale that gets the morality wrong.