27 years old Kim Rian lives with her older brother Kim Suho and his girlfriend Lee Joo Na. Rian has no memories on her father, her mother or any of her family member but with Suho by her side, she knows that none of them is important. 

"You have me. That's all you need. Trust me and trust me only and everything will be okay" - Suho

But their thoughts on what they're doing seems to be different from each other. His six years of girlfriend thought differently about the decision they've made.

"Because of her! I lost everything because of her! If only nothing happened five years ago, I won't be here" - Joo Na

And what will happen when Ri An knows the truth behind their dark secret? Will things be back to normal or is it too late for things to be normal again?

"So I'm not me, and you're not you. Then who am I? And who are you? - Ri An