Ri On tells Do Hyeon he was investigating what happened with Do Hyeon’s father, Seo Yeon, and Do Hyeon’s biological mother. Later, Do Hyeon stays the night in Ri Jin’s house. Ri Jin wonders why Ri On has such clear childhood memories when she has a few. Ri On reminds her of Mom’s explanation, that during a big house-fire when they were children, only she inhaled the toxic fumes which affected her memories. Ri Jin tells Ri On that she knows that they are not real siblings. Do Hyeon and Ri Jin go to the basement they kiss. Do Hyeon remembers that he was not the child abused instead it was the other child. Do Hyeon tells his grandmother that he will find out and reveal happened in the past. Do Hyeon’s mother finds out that Ri Jin is the missing child, and orders her men to kidnap her. Ri On tells Do Hyeon that Ri Jin was kidnapped, and Do Hyeon tracks Ri Jin’s phone. While trying to save Ri Jin, the men hit Do Hyeon’s head, causing him to remember everything. (Source: MyDramaList)