Definitely Neighbors depicts happenings around a divorced couple, who accidentally becomes neighbors after their divorce. Kim Sung Jae (Son Hyun Joo) and Lee Jung Soon (Ban Hyo Jung) are married couple. One day, the couple had an argument and their five year old son left the house. Their child died by a car accident. The guilt from their child’s death weighted heavily on the parents and eventually they divorced because of this. As time goes on, the ex spouses meet again as neighbors.