For many of the animals in New York's Central Park Zoo, life is good. Alex the lion (voice of BEN STILLER) is the star attraction and loves his daily allotment of steaks; hypochondriacal giraffe Melman (voice of DAVID SCHWIMMER) is sure he'll get any medical care he might need; and Gloria the hippo (voice of JADA PINKETT SMITH) is simply content there. Others, however, are not. When he overhears a bunch of penguins plotting to break out and head to Antarctica, Alex's best friend, Marty the zebra (voice of CHRIS ROCK), realizes he's not the only one suffering from wanderlust.
Accordingly, he breaks out one night, but the others' impromptu rescue mission results in them being tranquilized in Grand Central Station and then shipped off for Kenya. En route, however, the penguins seize control of the cargo ship and a sharp turn in course sends the crates carrying Alex, Marty, Melman and Gloria into the sea.
They wash up on what they think are the shores of San Diego, but are surprised to learn that it's really the island of Madagascar, ruled by King Julian (voice of SACHA BARON COHEN) of the lemurs and his top assistant Maurice (voice of CEDRID THE ENTERTAINER). The tiny inhabitants are happy to see the "New York Giants" since they'll likely keep the lemurs' mortal enemy -- the fossas (hyena-like predators) -- at bay. Yet, as Alex becomes upset that the others aren't following his every rule and especially when his native instincts kick in and he starts to get hungry, the animals try to keep order and peace in their new home.