Harrison Ford's Colonel Graff, a teacher at the school, narrates the spot, promising that while a previous alien attack crippled Earth, the planet won't stand for a repeat.
"If we're going to survive, we're going to need a new kind of soldier," Graff says. " ... We need minds like yours, Ender."
"I'll do everything I can to win this war," promises Ender, played by Asa Butterfield.
The trailer also gives a glimpse at the other characters peppering the film, including those played by Hailee Steinfeld, Viola Davis, Ben Kingsley, and Abigail Breslin. The adaptation of the classic novel hits theaters November 1.