The Fiery Priest follows Kim Hae-il, a Catholic priest with a fiery temper and sharp investigative instincts, who was formerly an elite NIS agent. When an elderly senior priest dies under mysterious circumstances related to a corrupt local cartel, Hae-il teams up with a cowardly detective, Koo Dae-young, and an ambitious prosecutor, Park Kyung-sun, to uncover the truth and bring the villains to justice. Blending high-stakes crime investigation with slapstick comedy and social satire, the series tackles systemic corruption in the fictional city of Gudam. Driven by his past trauma and a strong sense of justice, Father Hae-il does not hesitate to use unconventional, often violent methods to confront corrupt politicians, shady business tycoons, and local gangsters. Along the way, he builds an unlikely alliance with Gudam's eccentric residents, leading to chaotic yet heartwarming cooperative operations that capture the hearts of viewers.