Song Eunsu, Yang Haneul, and Kim Heechul have the same secret. They're all vampires. They haven't told anyone, and no one seems to suspect anything about them. What will happen when religious Choi Siwon falls for a vampire and learns the dark secret?

Kangin likes Haneul. Haneul likes Kangin. 

Siwon likes Haneul.

Eunsu likes Yoochun. Yoochun is oblivious.