Ender's Game Orson Scott Card

War breaks out between humans and an insect-like alien race called the Formics. The humans achieve a narrow victory then create the International Fleet (I.F.) and train gifted children to become commanders at their orbiting Battle School.

Andrew "Ender" Wiggin is born a "Third": a rare exception to Earth's two-child policy, allowed by the government due to the promise shown by his two older siblings. The eldest, Peter, is an intelligent sociopath who bullies Ender. His sister, Valentine, is deeply empathic. The I.F. removed Ender's monitoring device when he was six years old, seemingly ending his chances of Battle School. He is bullied by a fellow student, Stilson, but Ender violently attacks him. Stilson later dies from his wounds. Colonel Hyrum Graff visits Ender after hearing about the fight. Ender attests that by showing superiority now, he has prevented future struggle. Graff offers him a place in the Battle School.

Once at Battle School, Graff and the other leaders covertly work to keep Ender isolated. Ender finds solace in playing a simulated adventure game that involves being killed by and eventually killing a giant. The cadets participate in competitive war simulations in zero gravity, where Ender quickly masters the competition with novel tactics. To further wear Ender down, he is promoted to command a new army composed of raw recruits, then pitted against multiple armies at once, but Ender's success continues. Ender's jealous ex-commander, Bonzo Madrid, draws him into a fight outside the simulation, and once again seeking to preemptively stop future conflicts, Ender uses excessive force, and Bonzo dies from his injuries.

Meanwhile on Earth, Peter Wiggin uses a global communication system to post political essays under the pseudonym "Locke", hoping to establish himself as a respected orator and then as a powerful politician. Valentine, despite not trusting Peter, agrees to publish alongside him as "Demosthenes". Their essays are soon taken seriously by the government and the people.

Ender, now ten years old, is promoted to Command School. After some preliminary battles in the simulator, he is introduced to Mazer Rackham, a hero from the Formic war who saw key patterns in the Formic behavior. Ender participates in space combat simulations created and controlled by Mazer. As the fighting becomes harder, he is joined by some of his friends from the Battle School as sub-commanders. Ender grows depressed by the battles, his isolation, and the way Mazer treats him.

For his final test, under observation by I.F.'s commanders, Ender finds his fleet far outnumbered by Formic ships surrounding their homeworld. He sacrifices his entire fleet to fire a Molecular Disruption Device at the planet. The Device destroys the planet and paralyzes the surrounding bugger fleet. The commanders cheer and celebrate. Mazer informs Ender that the "simulations" were real battles, directing human spacecraft against Formic fleets via an ansible and that Ender has won the war. Ender realizes that he has committed genocide and become just like Peter.

Ender and Valentine join a group of space colonists. On their new planet, Ender becomes the colony's governor. He discovers a structure that matches the simulation of the giant game from Battle School and inside finds the dormant egg of a Formic queen. The queen telepathically communicates to Ender that before the first Formic war, they had assumed humans were a non-sentient race, for want of collective consciousness, but realized their mistake too late. Instead, she had reached out to Ender to draw him here and requested that he take the egg to a new planet for the Formics to colonize.

Ender takes the egg and, with information from the queen, writes The Hive Queen under the alias "Speaker for the Dead". Peter, now the leader of Earth and 77 with heart failure, recognizes Ender as the author of The Hive Queen. He asks Ender to write a book about him, which Ender titles The Hegemon. The combined works create a new type of funeral, in which the Speaker for the Dead tells the whole and unapologetic story of the deceased, adopted by many on Earth and its colonies. Ender and Valentine leave the colony and travel to other worlds, looking for a safe place to establish the unborn Hive Queen.