They come upon a large abandoned house which Yvan knows of – later discovered left by a Jewish family – and although Odile is reluctant to enter property that is not her own she is to learn that people act differently in times of war: the survival instinct comes to the fore, conventional laws are overturned. For a time then this becomes their home and they live in a style to which they're unaccustomed, admidst lush furniture with fine wine.
The family's wariness of Yvan soon lessons and he becomes a kind of older brother or father figure to the children, receiving Philippe's great admiration in particular. He steals from dead soldiers and sets traps for rabbits, fishes and provides for the family, even managing a kind of bemused respect from Odile when he tells her he'd like to marry her. A former teacher, Odile begins to teach the illiterate Yvan how to read and write. He also has a violent streak and is suspicious of any outsiders, being particularly mindful for the safety of Odile.
There's a blossoming of strong physical attraction between Odile and Yvan which climaxes in anal sex, and – after the short family idyll is ended by the police when they catch Yvan stealing and he's sent to a reformatory and Odile and children join the refugees – the mother struggles with her grief when she learns that Yvan has hanged himself but tells Philippe he's escaped.
Loss, emotional and physical turmoil, grief, hiding, lies, brief and improbable friendships and liaisons, such is the nature of France under Nazi occupation, which brings out the best and the worst of humanity.