I Am Number Four By: Pittacus Lore
We Are the last defense.
Four and Henri are aliens from the planet Lorien. There is an army of aliens called Mogadorians hunting them. With the help of his Cepen, Henri, his friend, Sam, his girlfriend, Sarah, and the school bully, Mark, he has to fight the Mogadorians. The futures of Earth and Lorien are in his hands.