The Arsonist involves the struggles of an undocumented immigrant family and a boy's coming-of-age. The son Kesuma must forge his own identity against the intimidating presence of his father Kakang, a man proud of his Javanese heritage and well aware of the social inequalities that allow his exploitation. Kakang counteracts by torching the property of those who slight him, leaving Kesuma simultaneously proud, fearful and ashamed. A clash of wills is all but inevitable. The film climaxes in a poignant conflagration, literal and metaphorical.

Mamat is a native of Kelantan, Malaysia, but he had left Malaysia many years earlier to join his brother Lazim in South Thailand in order to continue making his living as a trainer of fighting bulls (a Jogho). The practice had been outlawed in Malaysia but continued in Thailand. Mamat lives with his wife and three daughters, three divorcees and one who has not yet married, but he has sent his only son to boarding school in Kelantan. Mamat and Lazim are the leaders in a small village that depends mostly on the money won from gambling in bullfights for its sustenance. The story begins when Lazim is killed by Isa at the bullfighting arena.