The Book of Henry

Henry is a precocious 11-year-old who lives peacefully with his single mother and younger brother. He develops feelings for the girl who lives next door, but when he learns that her family is hiding a dark and dangerous secret: her abusive father is harming her. In order to protect her, he devises a plot to murder those responsible. When his mother finds the carefully crafted plans in his notebook, she decides to rescue the young girl.