Ender Wiggin, is the third child in his family, he was born to have both of his siblings traits, Valentine's love and compassion and Peter's knowledge and strategy. Ender and Peter do not get along, Peter hates Ender. When Ender got his monitor taken away Peter had a chance to take out his anger on Ender, Peter pinned him down on his bed with his hands around Enders throat. After pointing out that he could easily just kill him right then, he let him go. Peter is the bully of the family, but Ender has other bullies in his life. When his fellow classmates saw that his monitor was gone they also took their chance. In the end of that fight all that was left was his classmate, Stilson, on the ground with a bloody nose and several kicks to the stomach and groin. After passing his final test, having his monitor taken away, how he dealt with denial, Colonel Graff from the International Fleet selects Enderto go to Battle School. Ender said his goodbyes and left with Graff.
Battle School is located on a ship in space, far away from earth. On the flight Colonel Graff begins to isolate Ender by stating that Ender is the smartest kid and is better than all of the kids on that flight. Ender quickly becomes hated and has no friends. Ender gets to the Battle School, he and the new recruits live together and are called Launchies. After the first couple days of training Ender breaks his isolation and makes a couple friends, Alai and Shen. By being friends with Alai and Shen it helps Ender fit in with the rest of the launchies. In the battle room Ender quickly learns how to maneuver in zero gravity and learns how the freeze gun works. In Ender's free time he spends time on his desk playing a game called "Giants Drink", in this game he makes it farther than anyone else has. Ender does not know but the military commanders take notice of his progress.
Ender gets promoted to the Salamander Army. Alai and Ender say goodbye, and unexpectedly Alai whispers in Ender's ear "Salaam", which means peace to you. When Ender got to the Salamander army he befriended the only girl in the army named Petra. The commander, Bonzo Madrid set out the rules for Ender, he was not allowed to practice with the army or join in on the battles. During his free time Ender and Petra began to practice and he quickly catches onto the proper way to shoot and maneuver. In the evenings he began to teach his old launch group about what he has been taught from Petra. During a battle Ender disobeyed Bonzo, they were losing and four of the Leopard Army were about to open up the Salamander gate, Ender went out with frozen legs to protect his body and took careful aim and shot all four of the Leopards by the gate. After that game Bonzo punched him. The next morning Ender was traded to the Rat Army. He is put into Dink Meekers platoon and soon learns that Dink is an excellent toon leader. Ender does well in the battles and continues to teach his launch group every evening but his practices began to cause resentment among the other soldiers. One practice four older boys came to the practice and attempted to attack Ender, but Ender defended himself and left the boys injured. Ender realized that the teachers are leaving him to fend for himself.
Down on Earth Peter has convinced Valentine that they need to make a difference in the world. Peter and Valentine make fake adult accounts on the nets. Valentine's fake name is Demosthenes and Peter's is Locke, the names were based off of old geniuses. On the nets Val and Peter began to make a stand and are getting noticed by more and more people. Peters intelligence and Val's ability to write make people wonder about the world and what will happen after the bugger war. Will the world become chaos? Will wars break out? What will the world focus on? While Val and Peter begin to influence people on earth Ender turned nine years old and is now in a new toon under Petra's command. People are beginning to respect his brilliance and his practice sessions have many people attending, but he has become depressed and is stuck in the Giants Drink game. Colonel Graff visits earth to see Valentine to get her to write a letter to Ender, to help him carry on in the program. After Ender reads the letter his memory of Valentine helps Ender get a hold of himself and make it farther in the Giants Drink game. The teachers are relieved that the letter from Valentine helped Ender carry on.
Ender had been promoted to a commander, his new army is the Dragon Army. The soldiers in the army are mostly launchies and inexperienced. One of the soldiers is very much like Ender, his name is Bean, he is very smart, understands everything and is very bright. Ender focussed on teaching the basics to winning a battle, formations, shooting position and strategy. The Dragon Army was given many battles a day, and the opponent got advantages againstEnder, but the Dragon Army still won every time. He had many toons in his army, they act as independent units, this is a key strategy to winning, because it gives several different attacks on the opponent, which they do not expect. Bonzo his old commander got humiliated when Ender beat him in a battle. Bonzo trapped Ender in the shower room, when he was most vulnerable and attacked him. Ender beat him brutally. Ender was then transferred to Command School.
Back on Earth the authorities figured out about Peter and Valentines fake identities but decided to leave them alone and let them continue. Ender is brought down to Earth for a brief vacation and was visited by Valentine. After Enders vacation was done he was brought to planet Eros, where the International Command Fleet is located. Ender was introduced to Mazer Rackham, the hero from the second bugger invasion, he saved mankind. Ender went through many series of simulated battles, where he commanded an entire fleet. He soon learned that the buggers are highly evolved insects, which all act based on what the queen tells them. Ender began having strange dreams about the buggers and about Valentine. Ender began fighting more difficult battles, he was beginning to break down and so was his fleet. One day he got to the battle simulator and there were many observers and evaluators waiting to watch Ender in this battle. Mazer Rackham informed him before the battle began that this battle was his final examination in Command School, and that in this battle there would be new difficulties he had not faced before. Ender won the battle, but with a great cost, he had lost many ships and ended up blowing up the whole bugger planet. Ender soon realized that it was the real battle, he had destroyed the bugger population. Ender was so shocked he couldn't make sense of it in his head. He went straight to bed after the battle.
The videos of the battle had been playing all over Earth since Ender destroyed the buggers, Ender was a hero, but he didn't feel like one. Peter had taken control of the world and Valentine convinced Ender to go on a colonization mission to populate the worlds left behind by the buggers. Before he left with Valentine he learned that he had killed both Bonzo and Stilson, the bully from school. On the new planet Ender went out searching for an area where they could expand their population and found a scene from the Giants Drink game, the castle and the decaying body of the giant, the buggers had made this for Ender, they were prepared for his coming. He ventured into the Castle and found the last queen pupa, he realized that this was left behind for him to find so then he could find a place for the buggers to live. Ender became the "Speaker For the Dead" he has all the knowledge from the queen. The buggers never wanted to fight the humans, they came in peace but the humans had thought they were a threat. Ender felt all their sorrow. He made a promise, that he would find a place for the buggers to live once again.