Joon Jae becomes soft-hearted after seeing mermaid waiting for him so he brings the mermaid to his house. Mermaid is addicted to the new world of Joon Jae's laptop.
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. 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 3 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.
Jun Jae fall in a panic state after seeing Cheong is bedridden at hospital emergency room. Chi Hyeon receives investigation at the hospital. Nam Doo finds a listening device 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. 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 escaped prisoner, Ma Dae Young.
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. 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.
Jun Jae finds out that he is on the same path as his previous life so he decides to protect Cheong. 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 learned 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 are reunited and discuss what happened in their lives while they were apart. Nam Doo, who was curious about Kang Ji Hyun (Kang Seo Hee), asks Yu Ran about her. Chi Hyeon starts asking Seo Hee about his biological father.
After Cheong sees the end of her previous life with Jun Jae, she becomes confused and tries to conceal her thoughts from him. Meanwhile, Jun Jae starts gathering evidence that Seo Hee is harming his father in order to protect him from her.
Detective Hong, with the assistance of Jun Jae and Shim Chung, searches for evidence that Kang Ji Hyun murdered Jun Jae's father. Meanwhile, Chi Hyun approaches Nam Doo to suggest joining him. Ji Hyun and Chi Hyun plot Jun Jae's murder.
After Shim Chung is shot while defending Jun Jae, he stands vigil by her at the hospital. Professor Jin alerts Jun Jae that Ma Dae Young plans to visit his office for treatment of his amnesia. Jun Jae then alerts the police.
At the urging of Jun Jae, Shim Chung returns to the sea to prevent her death. She erases the memories of those who know her as she departs. Once she recovers from her injuries, she returns to Seoul. Jun Jae explains why he remembers her.
