In an alternate universe, the animated residents of Looney Tune Land are threatened by the nefarious Mr. Swackhammer, owner of the amusement park planet Moron Mountain. Desperate to attract more visitors, Swackhammer devises a plan to enslave the Looney Tunes as his new attractions. His diminutive alien minions, the Nerdlucks, are dispatched to capture the cartoon characters. However, the clever Looney Tunes challenge the Nerdlucks to a basketball game, leveraging their freedom against servitude, knowing that the aliens' small stature will ensure an easy victory.

When the Nerdlucks defy expectations by stealing the talents of professional NBA players, transforming into gigantic creatures known as the Monstars, the Looney Tunes realize they are outmatched. In dire need of help, they kidnap a recently retired basketball superstar from the real world to assist them. As the protagonist begrudgingly agrees to help his animated abductors, he is drawn into their zany world, full of slapstick comedy and cartoon physics. With the game approaching and the stakes high, they must work together to harness their respective skills and overcome their sizable adversaries.