Set over the course of twenty-four hours, BARBARIANS sees couple Adam (Rheon) and Eva (Moreno) wake up in their supposed dream house on Adam's birthday. Lucas (Cullen), property developer and friend of the couple, arrives for dinner with his actress girlfriend Chloe (Spiridonov), to celebrate Adam's birthday and the couple's buying of the house. But secrets unravel over dinner, and when the doorbell rings the evening takes a nightmarish turn. As manners give way to madness, an 'idyllic' evening of celebration descends into a dark night of terror; and the group's civilized dinner party turns out to be anything but.