In a gripping sci-fi tale set in the future, humanity is on the brink of launching a massive offensive against the home planet of an alien species known as the Formics, who had previously devastated Earth and claimed millions of lives. For the last fifty years, the International Fleet has been honing the skills of exceptionally gifted children, training them to become the commanders needed for this pivotal counterattack.
Cadet Andrew "Ender" Wiggin (Asa Butterfield), a remarkably talented young boy, catches the eye of Colonel Hyrum Graff (Harrison Ford) and Major Gwen Anderson (Viola Davis) due to his exceptional performance in simulated space combat. As a critical step in his training, they decide to remove Ender's monitor, which symbolizes the end of his support in the cadet program. However, things escalate when Stilson (Caleb J. Thaggard), a student that Ender previously bested in a combat simulation, attacks him. In an unexpected twist, Ender defends himself and inflicts significant injuries on Stilson, leading to emotional turmoil as he confides in his sister, Valentine (Abigail Breslin). Unfortunately, he faces additional harassment from his older brother, Peter (Jimmy 'Jax' Pinchak).
Unexpectedly, Graff reveals that Ender is still part of the program and they whisk him away to Battle School, where he is placed with fellow cadets but is treated as an outlier. In an environment filled with competition, Ender quickly excels in the zero-gravity "Battle Room," devising innovative strategies that outsmart even the older cadets. Graff assigns him to Salamander Army, under the command of Bonzo Madrid (Moises Arias), who resents Ender's presence. Fortunately, another cadet named Petra Arkanian (Hailee Steinfeld) takes him under her wing, providing private training sessions. Together, they defy Bonzo's orders during a critical match, leading to a significant victory for their squad.
While navigating the challenges of Battle School, Ender engages in a complicated mind game designed to push players into making tough decisions. One scenario presents an insurmountable problem, which Ender creatively resolves. A chilling encounter with a Formic within the game further complicates matters, especially when illusions of his sister Valentine and brother Peter trigger more profound emotions.
Progressing in his training, Graff promotes Ender to lead his own squad made up of trustworthy peers. As the battles intensify, Ender’s inventive tactics, including sacrificing team members for greater strategic gains, astonish Graff. However, tensions rise when Bonzo confronts Ender in the bathroom following a decisive match, leading to another tragic altercation where Ender seriously injures Bonzo. Overcome with guilt, Ender considers abandoning Battle School, but a heartfelt conversation with Valentine helps reaffirm his resolve.
Graff takes Ender to a former Formic planet, now a forward base, where he meets Mazer Rackham (Ben Kingsley). Mazer shares insights about the shared intelligence of the Formics and recounts a previous encounter where he disabled their fleet with a singular, bold maneuver. Understanding that the Formics function with a queen akin to ants, Mazer theorizes about the potential impact of destroying this queen during their upcoming assault.
As Ender trains tirelessly using advanced simulation technology, concerns mount over whether they are pushing him too hard. Regardless, as time slips away, Ender’s rigorous training continues in preparation for what lies ahead.
During his final test—viewed by several fleet commanders—Ender finds his forces vastly outmatched over the Formic home world. He daringly orders his fleet to sacrifice themselves to protect the Molecular Detachment Device long enough for a strike against the enemy, believing he was only simulating a game. To his horror, he learns that the destruction of the Formic home world was real, and he had commanded a real fleet, leaving him to grapple with the devastating weight of his actions; despite Graff’s declaration of heroism, Ender feels the guilt of being branded as a killer.
In the midst of this emotional upheaval, Ender stumbles upon a structure reminiscent of the castle from his mind game. Compelled by a need to understand, he rushes toward it and discovers a dying Formic queen, who is desperately safeguarding an egg.
In a poignant letter to Valentine, Ender reveals his plan to journey into deep space with the queen egg, determined to establish a new world for the Formics, seeking a chance for redemption.
