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.

Chinese eel farmer Chen smuggles himself into Korea to prove that his eels are safe to eat.

A desperate 35 year-old Young-sil is more than ready for full time job. And finally she gets a call from National security department as an intern. But her joy lasts no long, soon asked to leave. Accidently she discovers a secret about her boss and she suggest a deal of full time job to help him; secret spy.