Cockapoo Maggie and German shepherd Cody are brought in by their owners Diane and John, who have grown tired of Maggie's diva-like ways and cannot understand why she hates her pooch companion. Meanwhile, muzzled collie Marvin has left owners Laura and Dave at their wits' end. They are concerned by his lunging and nipping and fear he'll eventually bite someone. As trainer Jo begins the delicate process of earning Marvin's trust, there's no knowing how he'll react.