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.

Scandinavia, 1,000 AD. For years, One Eye, a mute warrior of supernatural strength, has been held prisoner by the Norse chieftain Barde. Aided by Are, a boy slave, One Eye slays his captor and together he and Are escape, beginning a journey into the heart of darkness. On their flight, One Eye and Are board a Viking vessel, but the ship is soon engulfed by an endless fog that clears only as the crew sights an unknown land. As the new world reveals its secrets and the Vikings confront their terrible and bloody fate, One Eye discovers his true self.

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.