Raised by her father, an ex-CIA agent, in the wilds of Finland, Hanna's upbringing has been geared to making her the perfect assassin. Sent into the world by her father on a mission, Hanna journeys across Europe, eluding agents dispatched after her by a ruthless intelligence operative. As she nears her ultimate target, Hanna faces startling revelations about her existence.

Two teenage assassins accept what they think will be a quick-and-easy job, until an unexpected target throws them off their plan.