Matthew and his girlfriend Rachel take a camping trip to an idyllic remote place in the country when suddenly, out of nowhere, Rachel disappears. For a year there is no sign of her and while Matthew is accused of her murder he falls into a deep depression, starting to doubt his own sanity. Then exactly a year to the day of her disappearance, Rachel returns to the very spot she went missing, with no belongings and no memory of where she's been. They begin to try and pick up their life together but it soon becomes clear that there is more to Rachel than meets the eye. In flashbacks Matthew has visions of her abduction by some kind of UFO, and the more he remembers the more she begins to change. As Rachel's transformation intensifies, Matthew starts to not only fear for his own life but for the whole of mankind! Who took Rachel, why has she been sent back and what is about to follow her...?