Two retired Pittsburgh boxers, Henry "Razor" Sharp and Billy "The Kid" McDonnen, have a heated rivalry that dates back thirty years. After each winning one bout against the other, a highly anticipated third fight to settle the score never occurs due to Razor's unexpected retirement. The two boxers, now in their sixties, have taken different paths in life post-retirement; Razor lives a simple, blue-collar existence, while The Kid has capitalized on his past fame and owns a car dealership and a bar. Despite their time away from the ring, their feud continues to simmer beneath the surface of their everyday lives.

An opportunity to reignite their rivalry presents itself when a boxing promoter, hungry for a profitable spectacle, entices them with the prospect of settling their grudge once and for all in a final match. The event, titled "Grudgement Day," quickly gains media attention, turning it into a viral sensation. Intrigued by a mix of personal reasons and the promise of a monetary reward that both fighters could use, they reluctantly agree to the match. As they begin their unorthodox training efforts, they are forced to confront old age, unresolved issues, and the complications of their past, including a shared history with a woman named Sally, which adds to the longstanding tension between the two adversaries.