When advertising exec Phil Winslow (Lee Pace) gets an offer to head the account for a California-based dog-food company, he uproots his wife (Judy Greer), three kids, and their beloved Great Dane, MARMADUKE (voiced by Owen Wilson), from Kansas to the Sunshine State. Once there, the big canine befriends a group of mutts at the local dog park, but after a surfing competition brings MARMADUKE celebrity, he turns his back on his new pals. Eventually, a disaster helps the oversized hound and Phil learn about the importance of family and friendship.