When the cast is removed from his severely broken arm, clumsy 12-year old Henry Rowengartner (Thomas Ian Nicholas) is shocked to find his arm has become a 100 mile per-hour thunderbolt. His throw from the bleachers directly to home plate alerts the last place Chicago Cubs and before you can shout "play ball!" he is signed as their new ace pitcher. With a few pointers from an aging star pitcher (Gary Busey) young Henry actually manages to pull of the impossible.