Young Catherine Morelli (Julie Christie), who lives in Rome, goes to Geneva to find romance at her father's wedding. There she begins a nearly nymphomaniacal pursuit of a mystery-fantasy man called Gregory (Michael Sarrazin).
A married couple grieving the recent death of their young daughter are in Venice when they encounter two elderly sisters, one of whom is psychic and brings a warning from beyond.
Chris returns from WWI unable to recognize his wife Kitty. He wants to reunite with Margaret, his former lover. Kitty hires a psychiatrist to address Chris's feelings for Margaret and cousin Jenny, but sees the man she knew is gone.
A scientist creates Proteus--an organic super computer with artificial intelligence which becomes obsessed with human beings, and in particular the creator's wife.