A couple moves in to a new house in the suburbs of Boston. They meet the couple next door. When Henrietta (Hen) and her husband have dinner at their neighbor’s home, she spots an object on the shelf that rings alarm bells: this belonged to a young man who was murdered. How did it end up here? Could her new neighbor, Matthew, really be a killer? He is a school teacher and appears ordinary, but Hen is sure he knows more than he is letting on. Hen becomes more obsessed and concerned that he is a murderer and may be planning his next kill.