Carlos Castle has only ever wanted one thing: to become a doctor. But when his brother's girlfriend mysteriously disappears from St. James University, he's forced to drop everything and come to her aid. After all, Carlos was the last to see Anna-they were together the night before-and now he has to break the news to his brother Jim. But it soon becomes apparent there's something much darker going on in 1899 North Dakota. Despite a massive search party, the trail turns cold, and Anna is nowhere to be found. With time ticking away, the Castle brothers are forced to turn to a determined sheriff and a strange scientist for help. Little do they know, their expedition into the mountainous terrain is about to get even stranger than before. One by one, members of the expedition start to disappear. It isn't until a family friend tracks them to a remote area high on Deer Mountain that Jim truly understands the gravity of what is happening: hidden in the mountain range is a cloaked time tunnel leading to the twenty-eighth century. In the future, North Dakota is a desolate wasteland, where humans are no longer on top of the food-chain and the aliens that control them have just one agenda-to take over the past, decimate the population, and breed the perfect human cattle from those who remain. The Castle brothers must use all their wits to survive this alien world and prevent the timeline they call home from being invaded.