The story takes place on the eve of Thai New Year, where Thai people celebrate the festival by splashing water on each other.
Jack is a police officer who has a warm family. One day he and his buddy named, With are ordered to check out a village where everyone dies mysteriously. There, Jack and With must face a horrific situation. All the villagers who have been dead rise again as zombies and eat everyone, including all the police officers in Jack’s unit. Jack and With can escape that event and call for backup.
After Jack escapes from the village, he starts to investigate the cause of the disaster. He gets a lead that all of this might occur from the contaminated water, and the town is located on the headwaters, which is why it affects that village first. So, Jack rushes to see the mayor and asks him to close the Watergate to prevent the rest of the people in town from using that water.
After they turn off the valve, Jack is arrested by soldiers. The truth reveals that someone in the military involves in the contaminated water that caused the disaster. The situation is out of control. The hoard of zombies is heading to the city where Jack's family lives…