Un Alma Pura (1965)

Second of two films that make up the collaborative film "Los Bienamados" (The Beloved, 1965). Claudia, a young aristocratic girl travels to Switzerland to recover the corpse of her brother, Juan Luis. As she flies back home to Mexico, in flashback it is revealed that she and her brother had an incestuous relationship and that she managed to drive his fiance, Claire, to her death... with tragic consequences for all of them.