Adam never had a good childhood; his father was an alcoholic and his mother was scared to stand up to her husband. Adam is put into care, but the abuse he suffered as a child has scarred him and he is unable to control his anger and behaviour - leading him to bounce between foster homes and engage in fights.
When he's 21 he discovers that his father is dying and goes to visit him in the hospital. His father gives him a wooden box and tells him that he loves him, even though he never showed it. Watching his father die, he takes the box home and eventually looks inside.
What he finds surprises him and makes him think differently about his past and future.