14-year-old Arrietty and the rest of the Clock family live in peaceful anonymity as they make their own home from items "borrowed" from the house's human inhabitants. However, life changes for the Clocks when a human boy discovers Arrietty.

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.