Luhan, a young boy that lived in a place called Mermaid’s Lagoon. He is part mermaid since his mother is a mermaid. His father is a human who fell in love with a mermaid and was turned into a mermaid after Luhan was born. This makes Luhan immortal.

Sehun, a young boy that lives in Seoul, Korea. His dream is to become a singer and get marry to the person he loves. He loves to read about mermaids. Some people call them sirens. Sirens are female mermaids that sings a song that will charm men to go to their ocean. Then the men will drown and gets his heart eaten. Sehun wishes he never have to meet a siren ever in his life.

Luhan decided to be a human for a while before going back home and be the prince of the underwater world. He would have to marry a siren so they can continue the breeding. Of course Luhan didn’t wish to marry the siren. The siren was Yoona, the daughter of Sir Taemin. Yoona is a sweet girl but she can be really needy. She wants Luhan with her all the time. So Luhan escaped to the human world, but he knows Yoona will soon be on his tail in the human world. So he must find love quick!

Sehun must be careful… what he doesn’t know is that a siren is about to disturb his life once and for all. Will Sehun & Luhan meet and fall in love or will Yoona claim the heart of the Prince? Love can be dangerous but who is willing to take the risk? After all, the price of love will be a heart. Sehun’s heart.