Raised in the remote Polish forest by former CIA operative Erik Heller, fifteen-year-old Hanna possesses extraordinary
survival skills and lethal combat training, though she knows nothing of the outside world. Erik is not her biological father, but rather a man who rescued her as an infant from Utax, a clandestine CIA facility run by the ruthless Marissa Wiegler. Utax was home to "Project Larson," an unethical program experimenting on infants by splicing their DNA to create elite, emotionless supersoldiers. When Hanna’s teenage curiosity leads her to inadvertently alert Marissa of their location, Erik is forced to flee, splitting up with Hanna. Erik tasks her with meeting him at a rendezvous point in Berlin while he goes off the grid.Stranded in the wilderness, Hanna is rescued by an unsuspecting British family on holiday, integrating briefly into normal teenage life and experiencing her first romantic feelings for a boy named Sophie’s friend, Anton. However, Marissa’s relentless agents quickly close in. Marissa, who initially viewed Hanna as merely a target to erase her own past operational failures, becomes deeply conflicted, developing a maternal obsession with the girl. Meanwhile, CIA agent Marissa orchestrates traps, but Hanna outsmarts them, eventually reuniting with Erik in Berlin.There, the dark truth of Hanna’s origin is fully unveiled. Hanna learns she was created using DNA from traumatized mothers, engineered to lack fear. Furthermore, she discovers that Dieter, the man she believed was her biological father, was actually a scientist murdered by Erik during the
rescue mission years ago. Despite this shattering betrayal, Hanna and Erik forge an unbreakable bond, fighting back against the cascading waves of CIA hit squads.Seeking answers, Hanna infiltrates the very facility where she was born, discovering other surviving girls like her, specifically Clara, who has also been conditioned for combat. Recognizing that Marissa is actually searching for redemption from her superiors, Hanna helps free Clara from the facility's psychological conditioning. Erik suffers fatal wounds during a desperate shootout with corrupt CIA elements attempting to purge the failed project. Devastated by the loss of the man who raised her, Hanna goes on the run in Europe alongside Clara, vowing to protect her "sister" and dismantle the corrupt shadows of the Utax program once and for all, while evading both Marissa—who attempts to operate as a rogue ally—and the chillingly efficient new agency assassins hunting them.