Kang-se discovers that Ki-sik is not Marie's biological father and begins to suspect his brother, Poong-ju, may be connected to her birth. While Kang-se secretly pursues the truth, Poong-ju learns that Marie and Sol are not siblings and shares both troubling and hopeful news with Marie, including the possibility of a bone marrow transplant. However, Kang-se is shaken when DNA test results suggest an unexpected family connection, putting his relationship with Marie at risk.