School student Wang Cai is tasked to research on the history of Pulau Ubin. While searching for information on the Internet, he is drawn into the world of the mythical island. He stumbles upon Xiang Qi, Zhu Pa and Wa Wa in a foreign yet familiar world. To find his way home, Wang Cai tricks the trio to dive into Temasek Ocean, only to be confronted by the Third Prince of the Southern Seas, protector of Temasek Ocean. What will happen to them in Temasek Ocean? Will Wang Cai finally return to his own world? Or will he succumb to the terror of the Third Prince?