Twilight Sparkle is living in an empty Equestria: a world in which she is the Omega Pony, the only pony in the population. When an alien pony named Belief shows her face to Twilight, she intends to convince her that this is not her true home, and if she does not realize that she is trapped in a false reality, she may remain alone forever, and never see her friends again. This would bother Twilight, naturally, except Twilight seems pretty content alone. Furthermore, she doesn't even remember that she HAS friends!