A bride's wedding night takes a sinister turn when her eccentric new in-laws force her to take part in a terrifying game. Young brothers Alex (Mark O'Brien) and Daniel Le Domas (Adam Brody) witness the killing of a man on the night of his wedding to their Aunt Helene (Nicky Guadagni). Thirty years later, Alex has returned home to marry his fiance, Grace (Samara Weaving), a former foster child eager to finally have a family. On their wedding night, he tells her that, as tradition, every outside addition to the family must play a game...