Battle School is an Earth-orbiting space station that trains and evaluates military child prodigies, with the goal of finding the leader they need to win the war.
Ender is exposed to significant emotional anguish and physical danger, but it soon becomes clear that he is an exceptional individual, even among the elite students.
Ender excels in academics, his main interest being a team-based three-dimensional laser tag competition in the zero-g Battle Room.
After Ender masters the game, it changes from one with direct control of ships to one where he relays commands to his classmates from Battle School: Julian "Bean" Delphiki, Alai, Shen, Petra Arkanian, Dink Meeker, Crazy Tom, Hot Soup, Fly Molo, Vlad, Dumper, and Carn Carby.
Under the tutelage of Mazer Rackham, the legendary savior of humanity in the previous war, Ender and his trusted companions take on a grueling series of ever more difficult battle simulations and emerge victorious every time.
Instead of fighting a hopeless battle against the enemy, Ender orders his squadron leaders to conduct a series of seemingly purposeless skirmishes.
He also learns from the Queen that the Buggers regretted having mistakenly fought humans and forgive Ender for destroying their world.
Ender writes a book anonymously called The Hive Queen, which tells the story of the war from the Formic perspective and starts to change public opinion of him.
Peter, who has become the Hegemon, the head of the world government on Earth, recognizes Ender as the author and asks him to write a second work, about him.
Thanks to his portrayal of himself in his books, The Hive Queen and The Hegemon, Ender is despised as a xenocide: the killer of an entire intelligent species.
When he arrives at the planet 22 years later (relativity having aged him less than two weeks), he finds that the original call for a Speaker has been rescinded.
While in dialogue with the Children of the Mind, the planet's religious monastic order, he is annoyed by Jane's commentary and turns off his connection to her.
Jane, without consulting Ender, sends incriminating reports to the interstellar authorities, who order the arrest of Miro and Ouanda, the researchers who have been investigating the piggies.
The Formics have an immune system that is advanced enough to protect them, and the humans have been using anti-viral dietary supplements, but both defenses are starting to fade in the face of the virus' mutations.
The existence of the new Formic colony is not general knowledge, but Ender knows that their appearance and their non-human way of reasoning would cause friction with the humans.
Novinha's youngest children Grego, a rabble-rouser among the humans, and Quara, who sees the virus as sentient and is bringing up objections to the research her mother and sister are doing, are troublesome.
Research ordered by the government on another planet, Path, leads a young genius, Han Qing-jao, to deduce the existence of Jane, who is tied to the ansible system.
Jane reveals herself to Qing-jao in an effort to prevent her from informing the authorities by telling her that the OCD her people suffer from was governmentally orchestrated.
However, the report to the authorities is still dispatched and the government enacts a plan to temporarily deactivate the ansible network to purge Jane from the system.
Qing-jao's father agrees to help with the descolada problem regardless of his daughter's actions, in exchange for a cure for the OCD that plagues them.
In the beginning young Val suffers the most, because Ender is the least interested in her mission, until it is revealed that she, along with Miro and Jane, are looking for the home planet of the descolada virus.
This causes Ender to collapse while working in the monastery garden, falling in and out of consciousness for the remainder of the book until his death.
Upon arrival at Shakespeare, Ender easily crushes Morgan's attempted coup, with help from Hyrum Graff back on Earth.
Ender's first stop, at the request of Hyrum Graff, is the Hindu colony of Ganges, which is governed by Virlomi, a former Battle School student who caused an uprising in India before she was subdued and exiled by Peter Wiggin's Hegemony.
Once there, Ender agrees to help Virlomi quell an uprising by a group called the Natives of Ganges, led by a young man named Randall Firth, who is under the delusion that he is the son of Achilles de Flandres.