In a covert Romanian facility, Erik Heller evades security to rescue baby Hanna; fifteen years later, father and daughter live deep in the Polish forest; Erik has trained Hanna to be an incredible killer and hunter, but she ventures away from home.
After her capture by Marissa's men, Hanna must fight to escape from the Moroccan CIA facility and join Erik in Berlin; along the way, she meets Sophie, a British teen on holiday with her family, who gives Hanna her first true taste of the real world.
Hanna and Erik are reunited in Berlin, where they hide out with his old army friends and she learns more about her father's past, but Hanna continues to long for the normal life she glimpsed with Sophie; Erik and his friends prepare for an attack.
Erik is holding Marissa prisoner, trying to negotiate a deal to get him and Hanna safely out of Berlin; Hanna hides out with Dieter and his family; desperate to know more about what her father is up to, Hanna discovers a huge secret in her own past.
Still reeling from her revelations about Erik, Hanna hides out in suburban London with Sophie, who is keeping her new friend secret from her parents; Sophie persuades Hanna to attend a school party where Hanna experiences the thrill of a crush.
Sophie and Hanna's relationship begins to turn sour over their shared interest in Anton; in the fallout from this argument, Marissa arrives at Sophie's house pretending to be Hanna's mother; Hanna finds herself torn between two choices.
Realizing that Hanna will no longer accept anything but the full truth, Erik takes her back to Romania so she can learn more about her past; Marissa begins to sense that Sawyer has not been telling her the full truth about Utrax.