Five months after his release from prison after serving a twelve-year sentence, arsonist Yeo Hee-soo terrorizes the city of Seoul with a series of deadly blazes.

Yeo rigs each fire so that a second, far more lethal conflagration ignites shortly after the firefighters have arrived, causing further casualties.

He then turns his attention to those members of the department he feels are interfering with his "mission", which develops into a game of cat and mouse with veteran fireman Jo Sang-woo.

Instead of using miniatures, it was filmed in real buildings throughout Busan using a special synthetic oil that allowed the crew to use actual fire.

For a key scene involving a gas station, a life-sized set was constructed and detonated at a cost of US$250,000.