"Sang Thong" tells the tale of a royal couple longing for a son to inherit the throne. But when Queen Juntayvee gives birth to a golden shell instead of a child, the king is furious. Though he still loves Juntayvee, his second wife, Junta, convinces him the shell is a curse. Juntayvee is cast out of the palace, banished to live in the forest with her aunt and uncle.

Meanwhile, Junta becomes pregnant too, hoping to bear the king a son—but she gives birth to a daughter, Juntee. In secret, Junta had tried to have Juntayvee killed, but her plan failed. Juntayvee survives in exile, and five years later, her true story is far from over…