A group of humans attempt to escape a global nuclear war through the use of time travel. However, something goes wrong with Sam Mitchell's pod, flinging him far into the future, into a time where humans no longer exist and a race of sentient ponies now thrive as the dominant life form. He eventually comes to the attention of a certain purple unicorn, who aims to learn all she can of Sam and his civilization as well as help him adjust to his new life.

Can Sam handle living as the only human? Can Equestria, and Twilight in particular, handle the changes this alien brings?