In Joseon, a vengeful crown prince and a memory-lost merchant mysteriously swap bodies, unraveling a web of chaos, secrets, and unexpected fate.

Hwa-ja has been raising three daughters alone in Busan after her husband passed away. One day, the second daughter Hye-young comes back to Busan after having continuous setbacks in Seoul. While spending time with her mom, she accidently sees a letter written in Japanese, which triggers her curiosity. She starts to ask Hwa-ja about her past life and gets to know new stories of her mother that she had never heard of.