Adolescent Kevin Katchadourian (Ezra Miller) is in prison after committing a massacre at his high school and killing his father and little sister using a high tech bow and arrow set. His mother, Eva (Swinton), a once-successful travel writer, lives alone in a run-down house and works in a mall travel agency in a town near the prison where she visits Kevin. She looks back at her memories of him growing up as she tries to cope with the anger and hostility of her neighbors, who know her to be Kevin's mother. Her memories are shown in flashbacks.
Throughout Kevin's life he has been detached and difficult. He does not bond with his mother; as a baby he cries incessantly, resists toilet training, rebuffs her attempts at affection, and shows no...