At the height of the Vietnam war, Captain Benjamin Willard is sent on a dangerous mission that, officially, "does not exist, nor will it ever exist." His goal is to locate - and eliminate - a mysterious Green Beret Colonel named Walter Kurtz, who has been leading his personal army on illegal guerrilla missions into enemy territory.
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. Along the way, the unlikely allies become friends but, when enemies attack, their quest takes on...