“Who cares about fame and fortune?” he said, clenching his fists in excitement and waiving them in the air. “I’m going to be a plush animal.”

The computer-animated “Bolt,” which opens in theaters on Friday, is the story of a German shepherd who has lived his entire life on the Hollywood set of his own television show, playing a superhero dog who battles evil to protect a little girl named Penny. His days of scripted triumphs come to an end, however, when a studio worker accidentally mails him to New York.

Trying to find his way home, Bolt meets a sarcastic, streetwise cat named Mittens (voiced by Susie Essman of “Curb Your Enthusiasm”). Still convinced he has superpowers  despite heavy mocking by Mittens  the two set off on a cross-country trek and are soon joined by Rhino. The hamster, so excited to meet his favorite TV star that he fogs up his ball, has memorized every nerdy detail of Bolt’s televised missions.

A lot of extra weight is riding on “Bolt” because it represents an effort by Disney to restore its animation division to prominence after a prolonged slump. “Bolt” is the first Disney film to be overseen entirely by John Lasseter, the co-founder of Pixar who took charge of creative matters at Disney Animation after Pixar was acquired by Disney in 2006 for $7.4 billion.

Disney dominated animation as recently as the mid-1990s, when “The Lion King” became one of the highest-grossing feature films in history. But Disney  reluctant to move into computer-generated animation  started bleeding talent to rivals like Pixar and DreamWorks Animation. The low point for Disney came in 2002 with “Treasure Planet,” a flop so terrible that the company was forced to restate its quarterly earnings downward by $47 million. Mr. Lasseter was not dainty in his retooling of “Bolt,” which was already deep in development when he joined Disney. He fired the original director, removed a snarky story line involving a radioactive rabbit and changed the central character to a white German shepherd from a brown mutt. He gave the newly installed directors, Byron Howard and Chris Williams, just 18 months to complete the reworked film, about half the time it takes to produce one of Pixar’s titles. (Mr. Lasseter’s pet chinchilla also provided the inspiration for Rhino; he had brought it to an animators’ retreat where its rolling around in an exercise ball led to the idea of a hamster instead of a rat.)