Coop and Remer are childhood friends who never grew out of their love for playing silly games. They find themselves as unemployed adults and watching basketball games on TV. One day, they invent a new game called BASEketball. It is a combination of basketball and baseball, where players shoot a ball into a hoop mounted above an elevated base, similar to a pitcher's mound, to score points. The game gains popularity when they start playing it in their backyard for fun and inadvertently attract a large audience.
Soon, a billionaire named Ted Denslow approaches them with an offer to turn their backyard game into a professional sports league. He backs their idea and the Professional Baseketball League (PBL) is born. The league is unique in that all the teams have the same name, the Milwaukee Beers, and they cannot change their city. The players are not paid based on skill or performance; instead, they all receive the same pay.
The Beers quickly become the most successful team in the league, with Coop and Remer as the star players. However, things change when Denslow dies and his greedy son, Baxter, takes over as the owner of the rival team, the Dallas Felons. Baxter wants major rule changes that would ruin the game and make it more profitable.
Coop and Remer are tasked with stopping Baxter's plans and ensuring that the game they created stays true to its roots. They face numerous obstacles and challenges, including personal issues and conflicts within the team and league.
In the end, Coop and Remer lead the Beers to victory in the championship game against the Felons and cement their legacy as the creators and saviors of BASEketball.