Religious fanatics inform historian Cameron Thorne that a medieval stone tower in Newport, Rhode Island is a secret portal—built by the Knights Templar—through which the Antichrist will appear. A group of Native Americans share this belief, claiming that the shape of Turtle Island, their name for North America, was revealed to them by ancient aliens passing through this same portal centuries ago. It all seems utterly ridiculous, until Cam's teenage daughter Astarte is kidnapped and dragged into an occult ritual designed to bring about the Apocalypse.