The Winslows go to the beach for some fun in the sun and Marmaduke hears the announcer tell about a fishing contest that the winner will win a year's supply of hot dogs. Marmaduke grabs a fishing pole and catches a shark that starts dragging him around. Marmaduke drags the shark onto the beach and causes a lot of commotion.
Marmaduke chases the shark towards the pier and the shark ducks behind a banner as Marmaduke runs up. Marmaduke lands on the weighing machine and springs up into a fish above a shop and then falls down onto the machine. The shark claims him as his catch and wins the hot dogs. Marmaduke is disappointed until Billy offers him his ice cream cone.