Aubrey and Paul Davison decide to celebrate their wedding anniversary by inviting their four children and their significant others to a family reunion at their remote and slightly rundown weekend estate. But the family reunion goes awry when their home comes under siege by a mask-wearing team of crossbow-bearing assailants. The family has no idea who's attacking them, why they're under attack, or if the attackers are inside or outside the cavernous, creaking house. All they know for certain is that nobody is safe.