This content has many provocative scenes. Please watch your back when reading. 

Seo Yi-Hwan, the youngest son of a conglomerate. He, with a close friend, who's a world-renowned pianist have enjoyed dangerous times committing themselves to promiscuous parties and drugs together. But soon, the walls of trust they've built slowly begins to crack as the mysterious girl, Yoo Se-Rin appears in the lives of the two men.

Who is this new mysterious girl?