Pittacus Lore 
I Am Number Four: The Lost Files: The Forgotten Ones 

In this thrilling 144-page companion novella to the New York Times bestselling I Am Number Four series, learn the fate of Adamthe Mogadorian-turned-ally of the Garde who risked his life to save Sam.Adam helped Sam Goode and his father, Malcolm, escape the Mogadorian base in Dulce, New Mexico. Using the Legacy that One bestowed upon him, Adam sacrificed himself and brought the entire facility crumbling down on his head.Miraculously, Adam survives in one piece, and he also discovers something incredible that the Mogadorians had been hiding from the Garde. Separated from his allies, Adam sets out on a quest to find the one thing the Garde have been missing all these years, the very thing that could turn the tide in this war.