When objects start to go missing from her home, Sophie Hartley (Susan Sarandon) suspects that a stalker is responsible. Then she meets Mara (Emily Blunt), the new co-worker of her husband, Craig (Sam Neill), and after seeing her in a dress that was among the vanished items, Sophie believes that Mara is obsessed with her. Unfortunately, she takes her suspicions too far, which leads to legal ramifications and her husband becoming concerned for her well-being -- but also to a startling discovery.