Humanity, having begun to explore the Universe and master interplanetary spaceflight, encounters an alien race dubbed the buggers. The discovery of a bugger forward base in the asteroid Eros leads to war between the species and the destruction of a bugger colonizing force. The battle to recapture Eros results in the discovery of advanced alien technology, including gravity manipulation. Political conflicts on Earth between three ruling parties, the Hegemon, Polemarch, and Strategos, are put aside in the face of the threat from the buggers. Ostensibly in preparation for the expected third invasion, an International Fleet (I.F.) is established, with headquarters on Eros. Increasingly advanced starships are built and secretly launched to attack the buggers' home worlds. To develop commanders capable of defeating the much larger bugger forces, the I.F. creates a crash training program for children with the best strategic minds, the Battle School.Protagonist Andrew Ender Wiggin is one of the school's trainees. He has a close bond with his sister Valentine but fears his brother Peter, a highly intelligent sociopath. The I.F. remove Ender's monitoring device, seemingly ending his chances of Battle School, and he gets teased by a fellow student, Stilson. Ender beats up Stilson before the fight is broken up unknown to Ender, the fight was fatal to Stilson. When explaining his actions to I.F. Colonel Hyrum Graff, Ender states his belief that, by showing superiority now, he has prevented future struggle. Graff, on hearing of this, offers Ender a place in the Battle School, situated in Earth's orbit, where Graff quickly isolates Ender from the other cadets.