It has been five years since Karen (Rachel McAdams) murdered her sister and disappeared with her infant nephew, Henry, in tow. Now, a new family is about to fall prey to nighttime terrors. A mysterious accident next door leads to teenage Addison (Olivia Cooke) and her family becoming the temporary guardians of Rowen (Logan Grove), a very creepy neighbor boy. Cameras installed throughout Addison's home capture the sinister events that unfold after Rowen's arrival.