Three women share a close bond that was deeper than any friendship. Song-ah, Senna, and Hyun-ah were both the same age and went to the same schools. Song-ah was an especially giving friend who would do anything for a friend. She absolutely trusted Senna and treated her like a sister along with her twin sister Hyun-ah. She thought they would always maintain a close relationship. But she had no idea that Senna was planning revenge.
The intent of the writer is to inspire viewers to never give up and keep moving forward with hope despite the many obstacles ahead of you. Like Scarlet O'Hara who said, "After all, tomorrow is another day. When people fall rock-bottom they can only go up from there. This is a story about Song-ah's tumultuous journey to find true happiness.