Eighth grade is set to be a good year for Diggy Lawson: He's chosen a great calf to compete at the Minnesota State Fair, he'll see a lot of July, the girl he secretly likes at 4-H, and he and his dad Pop have big plans for April Fool's Day. But everything changes when classmate Wayne Graf's mother dies, which brings to light the secret that Pop is Wayne's father, too. Suddenly, Diggy has a half brother, who moves in and messes up his life. Wayne threatens Diggy's chances at the State Fair, horns in on his girl, and rattles his easy relationship with Pop.
What started out great quickly turns into the worst year ever, filled with jealousy, fighting, and several incidents involving cow poop. But as the boys care for their steers, pull pranks, and watch too many B movies, they learn what it means to be brothers and change their concept of family as they slowly steer toward a new kind of normal.