After the events of "Ice Age: The Meltdown", life begins to change for Manny and his friends: Scrat is still on the hunt to hold onto his beloved acorn, while finding a possible romance in a female sabre-toothed squirrel named Scratte. Manny and Ellie, having since become an item, are expecting a baby, which leaves Manny anxious to ensure that everything is perfect for when his baby arrives. Diego is fed up with being treated like a house-cat and ponders the notion that he is becoming too laid-back. Sid begins to wish for a family of his own, and so steals some dinosaur eggs which leads to Sid ending up in a strange underground world where his herd must rescue him, while dodging dinosaurs and facing danger left and right, and meeting up with a one-eyed weasel known as Buck who hunts dinosaurs intently.

Cast:

• Eunice Cho - Diatryma Girl (voice)
• Karen Disher - Scratte (voice)
• Harrison Fahn - Glypto Boy (voice)
• Maile Flanagan - Aardvark Mom (voice)
• Jason Fricchione - Adult Molehog Male (voice)
• Bill Hader - Gazelle (voice)
• Kelly Keaton - Molehog Mom / Shovelmouth Mom (voice)
• Joey King - Beaver Girl (voice)
• Queen Latifah - Ellie (voice)
• Denis Leary - Diego (voice)
• Allegra Leguizamo - Aardvark Girl (voice)
• John Leguizamo - Sid (voice)
• Lucas Leguizamo - Aardvark Boy / Beaver Kid #2 (voice)
• Clea Lewis - Start Mom (voice)
• Jane Lynch - Diatryma Mom (voice)