Prologue:

Seven years ago, we have seen how the girls fought what's right and saved Summer and Sooyoung from the legions of darkness. Seohyun never lose her hope to win Sooyoung and completed her second family. They already discovered some of their body doubles, like: Summer and the little kid, Hyo. Right now, the girls had their journey to fame and one of the most famous girl group in South Korea.

"Right now, it's Girls' Generation." 

What if another enemy would stop them again?

What are they going to do if they knew that one of them is pretending to be like them?

"This is just the beginning of a sweet ending..."