Movie title

Hi, I'm looking for a movie in which I saw a brief scene: two women were sitting by a swimming pool. One of the women had a son and a daughter, both under the age of eleven. The daughter was in the pool, and the son of the other woman was bothering her. The girl started screaming, so her mother said to the boy’s mother, “Please stop your son from bothering my daughter.” But the woman replied coldly, “They’re just kids playing.” Meanwhile, the girl's brother, who was standing behind his mother watching the scene—and appears to be around the same age as the other children, and whom the film seems to revolve around—suddenly jumped into the pool and tried to drown the boy. The boy’s mother then shouted at the other mother, “Stop your son from bothering my son!” But she calmly responded, “They’re just kids playing.”