Alice, a professional mother of one, is hosting a playdate with friends at her upscale London home when a disturbed man breaks in. With her child in the next room, Alice panics and kills him—an act later ruled to have been in self-defense.

Everyone tries to encourage Alice to move on with her life—but with strange comments appearing online, a mysterious phone call telling her all is not as it seems, and her husband, nanny, and friends behaving strangely, Alice finds herself drawn to the mystery of who her intruder really was. As she digs deeper, she discovers a trail of dark secrets that spiral closer to home than she ever could have imagined.