The Time Slider - The Medusa Chronicles, #2

Ellie Johnson's back. And this time she's not alone! A young man's stalking her across the University campus, resurrecting nightmares of an alien invasion she's done her best to forget. He's hiding a secret that could ultimately lead to another confrontation with the Medusas. She knows they're going to return at some point. But before she can even contemplate facing them again, she has to work out whether the strange lad is doing something she thought was completely impossible. Travelling backwards in Time.