When Young-min and Mi-young marry each other after they graduate college, they experience different challenges that test their relationship.

Ha-Jin (Yoon Jin-Seo), Yoo-Jin (Shin So-Yul), Tae-Suk (Kim Da-Hyun) and Kyoung-Chul (Lee Si-Yeon) all attended the same high school. Due to an unsavory incident, Yoo-Jin disappeared. 10 years later, these four people are now at the same place. The next day, Yoo-Jin, who is a budding novelist using the pen name of "Jin-Jin," is found dead. The other three are now suspects. Veteran detective Dae-Sik (Kim Min-Sang) tries to solve the case.

Gang-cheol is a legendary street fighter in Busan who cleaned up his act to care for his sick mother. Knowing he's desperate for money for his mother's operation, Sang-gon proposes that Gang-cheol works for him.

Eun Guk and Eun Soo are siblings living alone after their father passed away. Eun Guk works at the post office. He feels like he is getting older, because of his younger sister's behavior like skipping school to attend an audition. Meanwhile, Eun Soo thinks her life is weary even though she is only 10-years-old. She thinks that because of her older brother, she can't pursue her dreams. Eun Soo then decides to leave for Seoul to achieve her dreams. One day, their mother appears in front of them.

Han Jung-woo, a pilot with top-class skills, is flying high and even appears on a famous TV show. But everything comes crashing down when a careless mistake causes him to lose everything, even his job. Blacklisted in the industry, no airline is willing to hire him. Desperate with no other choice, Han Jung-woo transforms completely into his younger sister's identity and succeeds in landing a job as a pilot.

During the Japanese colonial rule of Korea, while people are in despair, Jae-ho tries to raise morale by winning cycle championship. Bok-dong, who started cycling with Jae-ho just to make a forture, becomes a symbol of hope for Koreans by defeating Japanese cyclists.

Jung-ho, whose estranged wife is found dead, is suspected of murder but remembers nothing about the evening. Will his memory return? Is he innocent?

Trainee policeman, 'Sung-min' and job seeker, 'Jun-hyeok' were suspicious about a suicide incident of a girl who lived in the same dormitory, and they will be tracking her SNS account with the help of a private detective agency hacker, 'Nu-ri'. The investigation which started out of chivalry leads to uncontrollable consequences. These three people, Jun-hyeok, Sung-min, and Nu-ri become targets of SNS crime.