Inspired by a classic Joseon legend from Korea's first collection of unofficial historical tales, about a fisherman who capture and kidnapped a mermaid, this drama tells the love story between the son of a Joseon noble family named Kim Dam-ryeong (Lee Min-ho) and a mermaid he named Se-hwa (Jun Ji-hyun).When Dam-ryeong was a kid, he almost drowned but was saved by a mermaid. Following the incident, they became friends and Dam-ryeong named her Se-hwa, after his younger sister. They ended up falling in love, but one day Dam-ryeong was forced by his family to marry another girl. Devastated by the news, Se-hwa decides to leave Dam-ryeong forever and erased all his memories of her and their love. However, fate brings them back together and they tried to escape from humans who were going to separate them. Fearing that the same ill-fate that afflicts himself and Se-hwa will replay itself, Dam-ryeong sends an artifact to be discovered in the future to try and warn his future self. The fates of...

Plot Na Bong-Sun (Park Bo-Young) works as a sous chef. Because of her timid personality and low self-esteem, she doesn't have any friends. Since she was a child, she has been able to ghosts because of her shaman grandmother. One day, she becomes possessed by seductress ghost Shin Soon-Ae. Kang Sun-Woo (Cho Jung-Seok) is a star chef. Na Bong-Sun has a secret crush on him. He is good looking and confident as a chef. Even though he is popular with women, he has yet to get over his ex-girlfriend. He begins to notice Na Bong-Sun after her sudden change. Written by mahaar92

Hwang Shi-Mok had brain surgery when he was a child, which caused him to lack emotion. Now, Hwang Shi-Mok works as a prosecutor. He is rational, but cold and lonely. He is also one of the only prosecutors not involved in corruption. One day, a dead body is thrown in front of him. He meets Police Lieutenant Han Yeo-Jin at a murder crime scene. They work together to eradicate corruption at the prosecutor's office and solve a serial murder case.