Having been promised the 'trip' of a lifetime by their Irish friend and mushroom expert Jake (Jack Huston), a group of American teenagers arrives in Ireland, keen for adventure. Despite Jake's warnings about the "shrooms they shouldn't eat," things start to go horribly wrong when one of the five American tourists, Tara (Lindsey Haun) munches a "Death's Head" fungus and immediately suffers convulsions and dark visions. While confined to a tent that night as the others listen to Jake's ghost story around the campfire, the horrific details of this barely-overheard yarn from the man who brought her out of convulsions becomes Tara's new reality. The next day, as the group is bloodily whittled down to one, it is eventually becomes clear that, whether or not Tara's apparitions are real, the carnage they leave behind certainly is. Since everyone is now high on "shroom tea," it's anyone's guess who will last the longest. Will the jock Bluto (Rob Hoffman) succumb to the talking cow, or the succubus in the muddy car? Will long-haired Molly (Alice Greczyn) perish at the hands of the Texas chainsaw-type guys, or the dog-boy? Will bitchy Lisa (Maya Hazen) be snared above or below the reedy lake water? Will martial-arts wannabe Troy (Max Kasch) get gashed in the forest clearing, or abandoned orphanage hallway? Will Jake die from his jump through an upper window, or due to an axe in his brain? Even after a helicopter locates the sextet's lone survivor, and a land ambulance takes her toward the hospital, the slaughter will continue.