Un sac de pierres (2017)

Martin, a troubled teenager lives with his father and his younger brother in a house in the middle of a forest in Southern France. Martin suffers from the fact that his father only has eyes for his younger son and so Martin decides to kills his brother. On a spring morning, when the brothers go out fishing together as usual, Martin follows up on his plan by drowning his brother with a bag of rocks. He then naively hopes that he can win back his father's heart.