Ten year-old Edmund Hooper lives with his father, Joseph, in the large house Joseph has inherited. They are not close. Joseph hires a live-in housekeeper, Helena Kingshaw, who moves into Warings House with her ten year old son, Charles. Edmund is not happy about this; he is not looking for a playmate and resents Charles' presence in the house. He also resents the way that Charles is included as if he was a member of the family and not the son of a member of an employee.
The Hoopers and the Kingshaws go to Leydell Castle, an old monument on the coast. Edmund falls as they are exploring, largely because Charles has been taunting him. He is hurt badly and takes some time to recuperate, during which Charles comes into his own and makes some friends in the neighborhood. He starts to quite enjoy life on vacation, which seems light, bright and carefree in comparison to the dark and doom-filled world of Warings. but it is short lived. Once Edmund feels better, he starts to bully Charles.
Joseph and Helena have grown closer and when they tell the boys that they are going to get married, both boys are horrified. Charles feels a sense of dread when he is told that he will be attending school with Edmund and that the two will be considered brothers. He drowns himself in the stream at Hang Wood. Helena comforts Edmund, who seems to be distraught and upset by Charles' suicide, but who is secretly feeling a sense of triumph because he no longer has to share his home with Charles and feels as though he is the king of his castle.
