Siyama is the story of three Thai youths who are transported back in time to an ancient village in the last period of Ayutthaya kingdom. They find themselves in the midst of a vicious war with Burma before Ayutthaya is burned down (in April 1767).

A police officer, a local guide and his daughter follow the trail of a prison escapee, Nasor, into a forest with many secrets, one of which relates to the death of Nasor's father by the father of the officer. As the group ventures deeper into the forest, the eerie realm unleashes its spiriits.

A group of young Muay Thai experts led by David are forced to use their deadly training to protect themselves when the local extortionist threatens to kill their mentors daughter if he doesn't give up his bar.