Set in an Antarctic emperor penguin colony, the film establishes that every penguin must sing a unique song (called a "heart song") to attract a soul mate. This is based in fact, since emperor couples court each other and recognize one another by their unique calls. One particular couple, Norma Jean and Memphis, pair up and produce an egg. The egg is left in Memphis' care while Norma Jean and the other females leave to fish for several weeks. While the males are struggling through the harsh winter, Memphis drops the egg, briefly exposing it to the freezing Antarctic temperatures. The resulting chick - the film's protagonist, Mumble - is tone deaf and completely incapable of singing. However, Mumble has an astute talent for tap dancing.

This ability is frowned upon by the colony's elders, who do not tolerate deviance of any kind. As a result, Mumble is ostracized throughout his childhood, with only his parents and his friend Gloria to turn to. Mumble then grows to a young adult, still half-covered in fluffy down. Through a series of mishaps - mainly a mad chase by a hungry leopard seal - the young penguin finds himself far from his home and within the carefree colony of the adélies - penguins small in stature, but fiercely loyal to those they call friends. He quickly befriends a small group of bachelors who call themselves the amigos - Ramón, the smallest of them, is the unofficial "leader" of sorts. The amigos quickly embrace Mumble's dance moves and assimilate him into their misfit group.

Mumble's joy at finding acceptance for his difference is cut short when strange "alien discoveries" occur; a long-frozen human excavator tumbles out from a glacier, and Mumble is intrigued. Driven by curiosity, he sets out to find answers. Tracking his way back to Emperor Land, Mumble inadvertently causes most of the colony to begin dancing while trying to impress Gloria. Noah sees the lack of fish as punishment from the Great 'Guin regarding Mumble's dancing. Exiled, Mumble vows to find the real cause of the famine, and travels across vast territories with his friends. By happenstance, the birds finally come face to face with a legion of huge trawlers, all laden with fish caught around the Antarctic coast. Mumble follows after them fearlessly, leaving his friends behind to preserve his legacy.

Mumble eventually ends up in a penguin exhibit at a marine park, and fervently tries to communicate with the "aliens" who surround him. When his pleas fail, Mumble nearly succumbs to madness after months of confinement in the sterile glass prison. When a child taps on the glass wall one day, Mumble is woken from his stupor and dances in response, whereupon the astounded humans finally pay attention. He is released to the sea with a tracking device, and leads the "aliens" home to his native colony. If anything is to be done, however, Mumble must first convince the colony, and overcome the ruling power of the pious elders, to deliver a message of distress to the curious humans.

Info courtesy of Wikipedia
 

Director: George Miller
Writers: Warren Coleman, John Collee, George Miller & Judy Morris

Elijah Wood ... Mumble
Brittany Murphy ... Gloria
Hugh Jackson ... Memphis
Nicole Kidman ... Norma Jean
Hugo Weaving ... Noah the Elder
Robin Williams ... Ramón/Lovelace
Johnny A. Sanchez ... Lombardo
Carlos Alazraqui ... Néstor
Lombardo Boyar ... Raul
Jeff Garcia ... Rinaldo
Fat Joe ... Seymour
Magda Szubanski ... Miss Viola
Miriam Margolyes ... Mrs. Astrakhan
Elizabeth Daily ... Baby Mumble
Alyssa Shafer ... Baby Gloria