In the future, humanity is preparing to launch an attack on the homeworld of an alien race, called the Formics, that had attacked Earth and killed millions. The Formic invasion was stopped by Mazer Rackham, who crashed his F-35 Lightning II into a Formic queen ship at the apparent cost of his life. Over the course of 50 years, gifted children are trained by the International Fleet to become commanders of a new fleet for this counterattack.
Cadet Andrew “Ender” Wiggin (Asa Butterfield) draws the attention of Colonel Hyrum Graff (Harrison Ford) and Major Gwen Anderson (Viola Davis) based on his aptitude in simulated space combat. They order the removal of his monitor, signifying the end of the cadet program.
Ender is then attacked by Stilson, a student he defeated in the combat sim, but Ender fights back and severely injures him. Ender confesses his grief to his older sister Valentine but is harassed further by their older brother Peter.
Graff arrives to reveal Ender was being tested and is still part of the program. Graff brings Ender to Battle School and places Ender with other cadets his age, but treats him as extraordinary, thereby subjecting him to being ostracized by the others.