Scrat's nutty pursuit of the cursed acorn, which he's been after since the dawn of time, has world-changing consequences -- a continental cataclysm that triggers the greatest adventure of all for Manny, Diego and Sid. In the wake of these earth-shattering upheavals, Sid reunites with his long lost family, and the gang encounters a ragtag menagerie of colorful new characters determined to stop them from returning home.