In the sweltering heat of 1890s Siam, Siang, a mysterious Muay Thai warrior with a penchant for rocketry, dedicates his life to restoring justice within the Buddhist temple of his upbringing. His mission is twofold: he aims to recover water buffalo stolen by cunning cattle raiders from the impoverished farmers of Isan and seeks vengeance against the shadowy figure responsible for the tragic murder of his parents.
On the other side of the spectrum is Lord Waeng, a formidable noble with grand aspirations to control the agricultural domain, intent on monopolizing the steam tractor market. To further his sinister agenda, he enlists the help of a hulking ex-convict and Siang, devising a ruthless scheme to set Isan's farmhouses ablaze, mercilessly slaughter cattle traders, and capture farmers. The plan leads to the indiscriminate slaughter of countless water buffalo, leaving hardworking farmers without vital draft animals necessary for cultivating rice. However, Waeng's henchmen soon find themselves entangled with Nai Hoi Singh, a powerful cattle trader possessing supernatural skills, evidenced by an enigmatic tattoo that catches Siang's eye.
As Siang attempts to steal Singh's prized cattle herd, he faces a momentary confrontation with his target but ultimately retreats. Seeking guidance, Lord Waeng consults Nai Hoi Dam, a former partner of Singh who bears a curse from him that deters him from sunlight. Driven by a relentless desire for revenge, Dam shares a chilling revelation: the only way to break Singh's magical hold is to acquire the menstrual blood of an untouched virgin—the daughter of a black wizard.
Feigning the role of a fellow orphan harmed by Singh, Waeng cleverly convinces Siang to ally with Dam. Together, they enact a scheme that catches Singh off-guard. However, in a shocking twist, Dam reveals himself to be the very person behind the deaths of Siang's parents. The tattoo that intrigued Siang serves as a symbol of the dark magic that intertwines their fates, steering them towards a bitter confrontation. Amidst layers of betrayal, an unexpected bond forms between Siang and a wounded Singh as they escape their mutual foes in a desperate quest for redemption.
Within the lavish halls of Waeng's palace, a startling truth emerges: Dam confesses that E'Sao, whom he claims as his daughter, is actually an innocent child he abducted. His ulterior motive unfolds as he plots to abuse E'Sao and incapacitate Singh with dark sorcery. Yet, Waeng, wise to Dam's wicked intentions, poisons him, only for the cunning black wizard to transfer his consciousness into Waeng's body, rendering him a puppet master.
As the chaos escalates, Siang confronts the Thief in a fierce battle, but he struggles against Dam's formidable power. However, when Singh regains his strength and gifts Siang with magical amulets from his own chest, the tide of battle begins to turn. In a courageous sacrifice, Singh engages in a perilous fight with Dam, giving his life to shift the battle's momentum.
With Singh's sacrifice fresh in his mind, Siang seizes the opportunity to unleash his enhanced magical abilities to defeat the dark sorcerer—Dam's powers hampered by Waeng's lingering essence. As the turmoil subsides, Siang and E'Sao unite, utilizing rockets to launch Dam directly into one of Waeng's tractors, culminating in a catastrophic explosion that annihilates both antagonists.
As the saga of struggle and redemption concludes, the resilient pair rides into the warm embrace of a setting sun on a resplendent buffalo, their connection strengthened through the trials they endured together.
