Mumble's son Erik is going through an identity crisis similar to the one his father had in the original film but may have to set that aside as he and his father attempt to save the colony from a giant iceberg that has blocked their way to the ocean. Erik encounters the Mighty Sven, a "penguin" who can fly! Things get worse for Mumble when the world is shaken by powerful forces, causing him to bring together the penguin nations and their allies to set things right. A subplot follows the adventures of two krill, Will and Bill, who stray from their swarm and head off to find their destiny.