Harry, Ron and Hermione continue their quest to vanquish the evil Voldemort once and for all. Just as things begin to look hopeless for the young wizards, Harry discovers a trio of magical objects that endow him with powers to rival Voldemort's formidable skills.

Eight years after the third film, the OSS has become the world's top spy agency, while the Spy Kids department has since become defunct. A retired spy Marissa is thrown back into the action along with her stepchildren when a maniacal Timekeeper attempts to take over the world. In order to save the world, Rebecca and Cecil must team up with their hated stepmother. Carmen and Juni have since also grown up and will provide gadgets to them.

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.

There is a new criminal mastermind at large (Professor Moriarty) and not only is he Holmes’ intellectual equal, but his capacity for evil and lack of conscience may give him an advantage over the detective.