Stags follows groom-to-be Stu and his friends on his stag do in South America. What was meant to be a week of drink, debauchery and fun takes a dark turn. Instead of boarding a flight back to the UK, the stags are sent to a lawless prison island run by two warring siblings.Quickly it becomes clear that the stags need to pick a side to have any chance of survival. Friendships are tested and life-long loyalty is sacrificed as Stu and his mates begin to question who will make it home alive.