If your kids like the previous Ice Age movies, they'll get a kick out of this one, too. It reunites the same main characters - Ellie, Manny, Diego, Sid, Crash and Eddie - in a quest that brings them face to face with dinosaurs (who apparently live below the Ice Age world).
Plot: Manny and Ellie are readying to have a child. Sid gets parent fever. Diego begins to feel his age.
Sid decides to adopt three eggs he's found, which later turn out to be dinosaurs (huge surprise). The rest of the flick is the main herd trying to rescue Sid, who's been taken away by the real mommy dinosaur.
Along the way, they encounter a new Australian-styled adventurer named Buck, who adds a lot of comic relief.