When humble rancher Rick Patterson marries movie star Sabrina Eastman, his son Josh (10) finds himself with a new step-sister, Lacey (14). Josh is an introverted boy who doesn't have a lot of confidence and Lacey is a spoiled Hollywood brat who's angry at Sabrina for not letting her have her own reality show. The two kids do not get along and neither do their respective dogs: Josh's dog Meatball is a scruffy, farm mutt who's laid-back and friendly; Cassie is a prim, spoiled, purse city dog who is not into country living. Rick and Sabrina go on their honeymoon for a couple of days, leaving Lacey and Josh in the care of Krystal, a hippie-trippy New Age neighbour. When Lacey sees some people outside the house one night, she starts to think someone is watching the house but Josh dismisses her fears. However, as Cassie quickly develops her 'country nose', she learns that Lacey wasn't wrong. She and Meatball discover that a pair of bumbling crooks, Louie and Terrance, are plotting to steal Sabrina's prized possession - the valuable North Star diamond. Josh and Lacey discover that they are not as different as they imagined, and soon they realize something is definitely going on around their house. When Louie and Terrance kidnap the dogs and trick Josh and Lacey into going on a wild goose chase to find them, the crime is afoot. Meatball and Lacey escape their captors and must team up to prevent the two criminals from getting their hands on the diamond. It's dog versus man in a slapstick battle of wits. All leashes are off!