As the mismatched herd migrates toward its only salvation—a hollowed-out log so insanely large, it puts Noah's ark to shame—it stumbles upon a pair of mischievous possums and their sister, Ellie (Queen Latifah), a lady mammoth who doesn't realize she's adopted. The pressure's on Manny to inform her of her species, since they may be the last two mammoths on Earth. He opts to break the news to her gradually, rather than hitting her with the rarely appropriate but unbeatable come-on line, "Hey baby, wanna save the species?"
The impending natural disaster doesn't come into play until the end, so to offer an additional threat, there are two sea-monster-fish-things that thaw from blocks of ice, hungry for mammal meat. But the real conflicts come from our heroes themselves. Manny must learn to be less bullheaded, Ellie must learn she's not a possum with a horrible weight problem and Diego must learn how to swim—real quick.
With its frosty color palette, Meltdown isn't nearly the feast for the eyes Finding Nemo is. Nor does it have the heart of Toy Story 2. But it does have laughs, and it gets them without dating itself with the tired pop-culture references of the overrated Shrek films. It's not a classic, but it's a lot of fun, and I'd be happy to watch these characters trek through another ice age. At this film's rate of weather change, there should be another one in about nine months.