Over her winter break, Riley, a college junior, is persuaded by her estranged parents, Kathy and John, to visit home to fix their fractured relationship. As Riley settles in, she discovers that her parents have developed an unsettling friendship with her high school ex, Gordon, and that mysterious children are now living in the house. A series of disturbing flashbacks reveal Kathy and John's time at an eerie, unconventional couples therapy retreat that promised to heal their problems through supernatural means. As the day progresses, Riley starts to uncover the dark and twisted truth of her parents' desperate attempts to mend the deep issues plaguing their family.