Ponniyin Selvan: Part I: The Chola kingdom is under threat from forces both internal and external, and with crown prince Aaditha Karikalan, his younger brother Arunmozhi Varman and the emperor, Sundara Cholar separated by situations, it is up to a messenger to ensure the safety of the kingdom. Can he succeed in his mission, especially with Karikalan's former girlfriend, Nandhini, plotting to bring down the entire Chola empire?