In a future where genetic engineering has cured humanity of all diseases and defects but has also produced a virus that kills all females by age twenty and all males by the age twenty-five, teenaged Rhine escapes her forced marriage and journeys back to New York to find her twin brother.

An expert at simulated war games, Andrew "Ender" Wiggin believes that he is engaged in one more computer war game when, in truth, he is commanding the last Earth fleet against an alien race seeking Earth's complete destruction.

After modern science turns every human into a genetic time bomb with men dying at age twenty-five and women dying at age twenty, girls are kidnapped and married off in order to repopulate the world.

Cat thought the Hydra epidemic was over, but when new cases arise, she must team up with an enemy to fix the vaccine before the virus spirals out of control.

After Ender Wiggin's triumph over the Formics, society has been altered by the destruction of unity between the nations, but Peter Wiggin, Ender's older brother, is determined to restore Earth's unity with the help of young warriors.