In the small town of Lawtonville, Illinois, Rusty, high school junior Danny Mitchell's beloved pet German Shepherd, is celebrating a birthday soon. Danny is giving Rusty a new engraved collar for his birthday off of which they can hang his license. However, before Rusty's birthday, Rusty, through a series of misadventures, goes missing without any identification. He eventually ends up with the Neeleys - father Virgil, teen-aged son Bill, and infant son Jeff - a poor itinerant family, as Virgil looks for work in the area. Danny assumes that the Neeleys stole Rusty, which was not the case. Beyond Danny jumping to this conclusion from which he does not budge, he runs into a larger problem with young Jeff, who believes Rusty, who he has renamed Gladly, is rightfully his. But Danny butts heads with Bill even more. Bill and Danny's dislike of each other seems to stem not from each other per se as they don't even really know each other, but what the other represents. As Virgil hopes to stay ...