Amber Liu is brokenhearted when Krystal, the girl she had loved secretly for a long time married her best friend Minho. On the night of their wedding, Amber got drunk in another friend's party, trying to ease her pain. There she meets a pretty girl named Kaye and she immediately made a connection with her. But just when things are turning better between them and Amber is convinced that she will be forgetting about Krystal through her, the girl just disappears, leaving a red shoe as the only clue on her identity. Now Amber wanted to find the owner of the shoe and she tried searching for her. But what if she finds out that Kaye is actually not a real girl, but a boy who just wants to be a girl?