Barny, although a Marxist, is intrigued by the mysteries of religion. In confession, she teases a priest, Léon Morin, but he is a young and intelligent man and ready to discuss anything.
Elisabeth and her brother Paul live isolated from much of the world after Paul is injured in a snowball fight. As a coping mechanism, the two conjure up a hermetic dream of their own making. Their relationship, however, isn't exactly wholesome. Jealousy and a malevolent undercurrent intrude on their fantasy when Elisabeth invites the strange Agathe to stay with them -- and Paul is immediately attracted to her.