The young code breaker Karnell works in the Swedish intelligence service during the Cold War. Having cracked a secret code he is drawn into a conspiracy that stretches throughout the Baltic Sea. It turns out that there is a leak codenamed Ramona within the organization and now they have to stop Ramona before it wrecks havoc.
With the impending ice age almost upon them, a mismatched trio of prehistoric critters – Manny the woolly mammoth, Diego the saber-toothed tiger and Sid the giant sloth – find an orphaned infant and decide to return it to its human parents.
Better watch out! The big guy in red is coming to town once again. This time, Scott Calvin -- also known as Santa Claus -- finds out there's an obscure clause in his contract requiring him to take on a wife.
Kay and Jay reunite to provide our best, last and only line of defense against a sinister seductress who levels the toughest challenge yet to the MIB's untarnished mission statement – protecting Earth from the scum of the universe.