Haunted by an unexplainable and unresolved trauma from her past and compounded by a string of eerie coincidences, Adelaide feels her paranoia elevate to high-alert as she grows increasingly certain that something bad is going to befall her family. After spending a tense beach day with their friends, the Tylers, Adelaide and her family return to their vacation home. When darkness falls, the Wilsons discover the silhouette of four figures holding hands as they stand in the driveway. This endearing American family is pitted against a terrifying and uncanny opponent: doppelgängers of themselves.