Alex the Lion, Marty the Zebra, Melman the Giraffe, and Gloria the Hippopotamus set out to return to New York after escaping to Africa. Dependent on the mechanical knowhow of the notorious chimpanzees and penguins, their plan inevitably goes awry and they find themselves stranded in Monte Carlo where they try to escape Europe from animal control led by Captain Chantel DuBois by joining up with a traveling circus by chance.

Led by the venerable Siberian tiger Vitaly, the animal-centered circus has seen better days. During the course of a tour through a series of European cities that ends in a fabulous big top in the heart of London, Alex, Marty, Melman, and Gloria help Vitaly the tiger, Gia the jaguar, and Stefano the sea lion rediscover their passion for show business and reinvent circus performance.

The film features Alex the lion (Ben Stiller), Marty the Zebra (Chris Rock), Gloria the Hippo (Jada Pinkett Smith) and Melman the giraffe (David Schwimmer) and King Julian (Sacha Baron Cohen).