SOS: A Prequel to The Silence of Six — E.C. Myers

Evan Baxter doesn't have much time left before he must do something that will change his life -- and the lives of his friends, his family, and millions of people he's never even met -- forever. There's only one person who could come through for him at the last moment, but that chance is fading fast. In the course of one day, Evan has to come to terms with pulling off the most daring and dangerous feat of his young life, and he may not survive to see the consequences.