In the year 1598, Dam Ryeong stayed at Yang's house. At the little pond, he met mermaid's eyes. Dam Ryeong felt sorry for the mermaid so he sent mermaid to the sea under the guise of Yang's crime. Hence, their long relationship started.

Joon Jae becomes soft-hearted after seeing mermaid waiting for him so he brings the mermaid to his house. The mermaid is addicted to the new world of Joon Jae's laptop. Meanwhile, Joon Jae and the mermaid become fugitive due to the chase of Jin Ok.

Jun Jae was left alone with a jade bracelet and a grain of pearl after falling from a cliff, he barely managed to arrive in Seoul and hurried in to resolve a fraud case of madam. Meanwhile, Mermaid begins a rough journey to Seoul to keep the promise.

Jun Jae, who had never seen a mermaid before felt a strange sense of vision and helped her escape from the aquarium... On the other hand, a murder happened next door to Jun Jae while the whereabouts of Ma Dae-young is unknown for three months.

Jun Jae feels strange about himself having weird feeling toward Sim Cheong. He warns Sim Cheong that if she does not tell him what happened in Spain by tomorrow, she should leave home. Sim Cheong fall asleep with a wish that the next day would not come.

Jun Jae fall in a panic state after seeing Cheong is bedridden at hospital emergency room. Chi Hyeon receives investigation at the hospital. Meanwhile, Nam finds a tape recorder that is attached to a black box inside of Chairman Huh's car.

Having lost the memory of Cheong in Spain, Jun Jae is confused by himself. He is caring about the presence of other man that Cheong speaks of. Meanwhile, detective Hong who has been looking for clues of the murder case encounters Ma Dae Young...

Cheong feels annoyed by Jung Hoon's advice so she asks bold questions to Jun Jae. On the other hand, Jun Jae felt strange about Nam's loss of communication. He contacted Nam again and Ma Dae Young receives the call...

Jun Jae is relieved to know that Cheong is with him now and looks after him. Meanwhile, Jun Jae is confused when it is discovered that the man who threatened him was an excaped prisoner, Ma Dae Young. Furthermore, He even approached Cheong also...

Jun Jae is increasingly troubled by Kim Dam Ryeong's identity who continues to appear in his dream and send messages. Meanwhile, Jun Jae and Nam Doo receive invitation from Jin Joo as planned.

Finding out that Jun Jae is a swindler, Cheong leaves home in disappointment and Jun Jae focuses on finding Cheong. Meanwhile, detective Hong who is chasing after Ma Dae Young finds out about Ma's new past, and tries to speed up the investigation.

Jin Joo feels frustrated that the investment was not carried out properly so she decides to meet Seo Hee again. On the other hand, Jun Jae is caught by detective Hong and he made a call to Cheong but no one answers the call.

Si Ah visits Jun Jae's house together with Yu Ran to win the favor of Jun Jae who likes the food cooked by Yu Ran. Meanwhile, Jun Jae discovers something strange when he is moving with the detectives to find evidence that Ma Dae Young kidnapped Cheong.

With the help of Professor Jin, Jun Jae finds out that he is on the same path as his previous life so he decides to protect Cheong. Meanwhile, Yu Ran finds out that Jun Jae has ran away from home when he was in high school and visits Seo Hee with rage.

Having learnt about Cheong's terminally ill heart, Jun Jae could not conceal his melancholy so he tries to tell her about what he saw in his dream. Meanwhile, Cheong decides her birthday and invites all her best friends.

Jun Jae and Yu Ran, whom they met again, talk each other regarding their past time. Nam Doo who was curious about Kang Ji Hyun(Seo Hee), asks Yu Ran about her. In the meantime, Chi Hyeon starts asking Seo Hee about his biological father.

When Cheong sees the end of her previous life with Jun Jae, she becomes confused and tries not to reveal her thoughts to Jun Jae. Meanwhile, Jun Jae starts gathering the evidence of eccentric Seo Hee to bring back his father from her.

After Chairman Huh's death, Jun Jae and detective Hong speed up their investigation and begin searching for evidence after receiving a search warrant of Kang Ji Hyun(Seo Hee). Meanwhile, Chi Hyeon approaches Nam Doo to suggest joining him.

Jun Jae suffers from unexpected circumstances that Cheong is unconscious after being shot instead of Jun Jae. Meanwhile, Ma Dae Young who lost his memory can not stand the loss of his memory so he tries to visit the professor Jin to find his memory back.

Cheong visits the people around her and says farewell before returning to the sea. Meanwhile, Jun Jae embarrasses the people around him with unexpected acts when Cheong has left from him.