Lexi Hooper was a Harry Potter fan since the very start. Now that all seven books are published, Lexi and her friend decide to go to King's Cross station for a memorable cosplay. But what started as a joke, turns out to be both Lexi's dream and her nightmare. Just for a laugh, Lexi starts to run towards platform 9 and 10, careful not to hit it too hardly. But the shocking part is, the wall disappears and she passes the barrier, suddenly finding herself in platform 9 3/4. At first she thinks that she's just dreaming and goes with the flow. But when she figures out that everything is as real as it can get, Lexi realizes that she has the power to change everything and save everyone; because she knows exactly what is going to happen next and how to stop it, even though she is just a Muggle.