19‑year‑old Lee Geum‑ja is sent to prison on false charges of kidnapping and murdering a child. In prison, the woman hatches a plan for revenge and wins the hearts of the inmates with her kindness, earning the name Kind‑Hearted Lady Geum‑ja. After serving 13 years, the avenger, with the help of her prison friends, sets out to find the person who ruined her life.