Colby (NICK WHITAKER) is a 14-year-old who lives in a rural part of the country with his parents, Terrence (CHRIS KENDRICK) and Claire Hatchett (CHRISTY SUMMERHAYS). While there are lots of dogs around since Terrence is a dog breeder, none of them are pets, much to Colby's dismay. He also worries about the dogs since his dad isn't particularly nice to them, which also holds true for the way he treats Colby and his mom.
Accordingly, Colby takes one of the pregnant breeder dogs away so that she can safely have her pups, but when his dad finds out, he's quite mad and throws a half-breed puppy away, telling his son to leave it in the abandoned house. Colby, however, returns there to get the pup and takes him to the safe haven that is the boy's fort deep in the woods.
Six months later, the dog has grown up and befriended another pooch that's been nicknamed Lizard Tongue by Sheldon (DUANE STEPHENS) and Livingston (RANDALL NEWSOME), two inept dog catchers who've been trying to capture the previously dumped pooch. Benji introduces Lizard Tongue to recluse Zacharia Finch (NEAL BARTH) while repeatedly trying to free his mom from the inhumane conditions where she's kept. Terrence hates having the nuisance dog around, but when he hears that a casting call has been made for the next Benji movie, he changes his tune.
As the local sheriff, Ozzie (NATE BYNUM), eventually gets involved and while the bumbling dog catchers repeatedly pursue the two canines, Colby must decide whether to stand up to his father for the way he's treated him, his mother and their dogs.