Life’s good for deliveryman Doug Heffernan, until his newly widowed father-in-law, Arthur, moves in with him and his wife Carrie. Doug is no longer the king of his domain, and instead of having a big screen television in his recently renovated basement, he now has a crazy old man.
Doug's parents visit while Carrie's on a business trip and take over running the house, making Doug feel like a kid again. Also, Arthur tries to strike it rich by inventing a new type of screwdriver called "the Arthur's head."