Hometown Legends S02E05 - Surrogate Mother

Kaeddongi was brought into the Ho household for the sole purpose of giving an heir. Turned out that she and Ho Seung have met as children and the two developed genuine feeling for each other. As soon as she had given birth, she was chased out of the home and was later murdered on order of Ho Seung's mother who wanted to put a stop to their affair once and for all. Her spirit returned 3 years later to protect her son who was being slowly poisoned by Ho Seung's wife.