After unsuccessfully trying to have a baby of their own, Dr. Kim Do-il and his father convince his wife Choi Mi-sook to adopt a child in an orphanage. Mi-sook is connected to arts and chooses the six years Kim Jin-sung that loves to draw trees. The boy becomes close to the eight years old next door neighbor Min-jee and is attracted to an old Acacia tree in their lawn. When Mi-sook unexpectedly gets pregnant, her mother asks her to return Jin-sung to the orphanage, beginning the rejection process of the boy. When the baby is born, Mi-sook does not treat Jin-sung well, who believes the acacia tree is his mother, and in a rainy night he vanishes. Along the next days, the family becomes insane, disclosing a dark secret about Jin-sung...