Just as any dog is loyal to his owner, so, too, are director Frederik Du Chau (2005's "Racing Stripes") and screenwriters Adam Rifkin (2006's "Zoom"), Joe Piscatella and Craig A. Williams in their big-screen adaptation of "Underdog." Based on the 1964 animated series, the film takes all of the tried-and-true archetypes and plot points of a superhero movie and replaces the human crime-fighter with one of the canine persuasion. All the bases are covered: there is a lab experiment gone awry that gives the hero-to-be super powers; there's a discovery of said heightened abilities and a decision to use them for good; there's a love interest who does not recognize her friend when he is in costume and starts to fall for his alter ego, and, yes, there is a deranged scientist with dastardly plans for destruction. Deviation from these well-established story points is rare, but "Underdog" is still an inspired family film that feels fresh because of its refocusing on a mammal with more than two legs.

Shoeshine (voiced by Jason Lee) is a lonely Beagle feeling jilted from his job as a crime-sniffing dog on the police force of fictional metropolis Capitol City. When he is dognapped and subsequently threatened with experimentation by crazy scientist Dr. Simon Barsinister (Peter Dinklage), Shoeshine narrowly gets away, though not before getting drenched in chemicals that give him powers beyond his wildest imagination. Found on the street by unhappy widowed father Dan Unger (James Belushi) and taken home with him, Shoeshine quickly befriends Dan's withdrawn 14-year-old son Jack (Alex Neuberger). Jack has never encountered a dog who can carry on a conversation, fly through the air, and has the strength of an animal one hundred times his size, and together boy and hound begin preparing Shoeshine to become Underdog, the enigmatic and courageous resident crusader of the city.

Filled with skepticism walking into the screening of "Underdog," my low expectations were slowly but surely surpassed by a big-hearted movie that delights in repeating and playing with the conventions of superhero pictures like "Superman" and "Spider-Man." "Underdog" cannot compete with those larger-scale blockbusters—it is, first and foremost, a movie catering to children—but it is funny and charming without going for lowest-common-denominator gags that usually litter today's family market.

The low-key romance between Underdog/Shoeshine and sassy Spaniel Polly Purebred (voiced by Amy Adams) is undeniably sweet, closely following the arch between Superman/Clark Kent and Lois Lane in "Superman," complete with a magical scene where they fly through the sky together. To add a twist to the formula, director Frederik Du Chau also throws in hints of "Lady and the Tramp" when they share a spaghetti and meatball dinner afterwards.

A little more tiresome is the dog/human relationship between Shoeshine and Jack. In a too often used cliché, Jack's mother has died and he's not getting along with his father. Leave it to Shoeshine, then, to bring them together. This very same premise was carried out in a much more resonant and effective manner in 2007's "Firehouse Dog," which also had the benefit of one of the most talented current child actors, Josh Hutcherson, playing the lonely boy. Here, the job goes to Alex Neuberger (2006's "Running Scared"), a capable young actor in his own right who nonetheless has some trouble emoting with conviction in the more dramatic moments. As pint-sized villain Dr. Simon Barsinister, Peter Dinklage (2003's "The Station Agent") has a field day playing broad and against-type, while Patrick Warburton (2005's "Rebound") is amusing as lunkheaded henchman Cad, who starts using 'P' words when the rest of his pocket thesaurus gets destroyed in a lab fire.

Clocking in at a brief 84 minutes (including end credits), "Underdog" is slight but cute, and will entertain children in the single digits while not sending their parents screaming for the exits. Jason Lee (2003's "A Guy Thing"), experiencing a popularity resurgence with his hit NBC sitcom, "My Name Is Earl," is plucky and likable as the voice of Shoeshine, and Amy Adams (2005's "Junebug") is appropriately adorable as the voice of Polly. The special effects that digitally give these live-action dogs an English-speaking human side are seamless. All things considered, "Underdog" won't be reinventing the wheel anytime soon, but it is smarter than the fair share of cinematic options families are given. In the same week when the insulting, materialistic "Bratz" is also opening, it's a comparative godsend.