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A coincidental switch of cars leads to a switch of fates for twins who were separated 30 years ago. Hae Kang, the elder sister is a successful lawyer married to Jin Eon the successor of a top pharmaceutical company. Their love marriage is shattered by the death of their daughter and her husband's affair with Seol Ri, which ultimately leads to their divorce. But before the divorce is officially declared, Yong Ki switches cars with Hae Kang to avoid being followed by people who are after her life. Yong Ki is the younger sister who is a pregnant widow trying to uncover the secrets behind her husband's sudden death. After the fateful encounter, Hae Kang ends up in a horrible accident (in the switched car) which makes her lose her memories. Baek Seok saves her and allows her to live with his family till she recovers but mistakes her to be his first love Yong Ki. Hae Kang as Yong Ki is no longer a cold and reserved person, instead she's warm, cheerful and caring. As Seol Ri and Jin Eon are in talks for marriage, he accidentally runs into Yong Ki. He is shocked at first but gradually begins suspecting that she's his wife and falls for her newly discovered bright self. She's shaken by his arrival too. (Source: Another Stranger at MyDramaList)