Unlikely hero Kevin Johnson didn’t know he had paternal grandparents until they showed up at his parents’ backyard Fourth of July party ... on a Harley ... wearing leather jackets. His father ignored them, told Kevin to say a polite hello and move on. Now Kevin has to go to rural Wisconsin and live with them. He expects a long and boring summer. His grandparents, however, turn out to be more interesting than expected. Grandma drives a yellow Mustang GT and is better at food preparation than the housekeeper Kevin had had at home. Grandpa runs Tchaikovsky Towing & Salvage, and Kevin is his new apprentice. Their first job is towing a drunk driver’s Corvette. 

The next day, Kevin’s grandparents drag him to church, where he sets eyes on the prettiest girl he’s ever seen. Surprisingly, she lives with her grandparents next door to his, not that it’ll do him any good. She’s way out of his league. Even so, she offers to help with his grandfather’s project. They’re duplicating the car that Kevin’s great-grandfather drove in the 1927 Indianapolis 500. But they’re doing more than restoring an old car. They’re after a posthumous pardon for the late great driver, whose career ended after being wrongfully convicted of manslaughter.