Alex the Lion is the king of the urban jungle as the main attraction at New York's Central Park Zoo. He and his best friends Marty the Zebra, Melman the Giraffe and Gloria the Hippo have lived their entire lives in blissful captivity, complete with lavish meals and their own park views. Not content to leave well enough alone, Marty allows his curiosity to get the better of him and, with the help of some prodigious penguins, makes his escape to explore the world he's been missing, intending to return before morning. In the middle of the night, Alex, Melman and Gloria discover their friend missing and decide the only course of action is to break out of the zoo and get Marty back home before anyone notices they're gone. Even in New York, a lion, giraffe and hippopotamus wandering the streets and riding the subway are bound to attract some attention. Alex, Melman and Gloria manage to track Marty down in Grand Central Station, but before they can catch the train home, they are darted, captured, crated and put on a ship to Africa by well-meaning humans who think they should be freed from the stress of New York life. When those plotting penguins sabotage the ship, Alex, Marty, Melman and Gloria find themselves washed ashore on the exotic island of Madagascar. Now, these native New Yorkers have to figure out how to survive in the wild and discover the true meaning of the phrase "It's a jungle out there."