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. Meanwhile, something inside Hwa-ja's heart where has been buried for decades also opens up.