When Nigel (Tom Sturridge), a student at an exclusive British private school, is murdered, his classmate Alex (Eddie Redmayne) emerges as the prime suspect. Dr. Sally Rowe (Toni Collette), a forensic psychiatrist, questions Alex, probing for the truth behind the crime. As Alex's father (Patrick Malahide) presses the police to drop the case, Rowe discovers shocking secrets about both boys and their possible connection to an earlier murder.