Season 1 of The Legend of the Mekong River premiered on 20 oktober 2020.

Phetai is an archeologist. She always dreamed of herself in traditional clothing and in an incident where she is killed. She was contacted to go analyze an old artifact but found that the artifact was fake. She met Songhop who has the same face as the person who killed her in her dream. Because of this, she hated him immediately. Even though they hate each other, fate seemed to bring them together multiple times. Their fate connects to the legend of “Nak Usa”, a land under the protection of the Four clans of Serpents (Nak). Phetai and Songhop found a slab that acts as a door to the Nak Usa land. This information was leaked to Artifact collectors that wish to possess the treasures of the Nak Usa as well. Phetai and Songhop race against time in an adventure to find the treasures in Nak Usa.