The story revolves around criminal investigation and forensic procedures in the late Chosun era, following the activities of an undercover special task force that was established to counter the increasing number of crimes resulting from political turmoil in the period. Kang Seung Jo and Kim Kang Woo lead the team of elite investigators as they uncover the circumstances behind mysterious deaths and other crimes.

A cops and robbers drama filled with emotion, Justice Heroes is a co-produced by FTV and the Ministry of Justice. The latter has collected 67 sensational real major criminal cases and 27 prosecutors stories.

The poor Lin Sheung-Chun (Esther Kwan) was sold into the Kwan family as a concubine to help pay off her father's gambling debts. However, on the night of her marriage, her husband died. Hearing her screams, Wang Yeuk-Lam (Michelle Yim), the first wife, rushes in. Seeing her husband's dead body, she assumes Sheung-Chun is the murderer and tries to stab her, hitting her head on a table in the process. Ever since, Yeuk-Lam believes that she is a young girl, and that Sheung-Chun is her mother. She has no memories of her previous life.

In the near future, a game development company, Cooltron, has developed a love game called "Listening to the Heartbeat". To promote the test game, Cooltron organizes a competition with a special bonus in which Yan Xiao Yu participates. According to the system, she is matched with engineer Ji Yun Feng. The ultimate clearance condition of this game is the heartbeat of both parties.

Shunsuke works part-time at a cafe owned by his uncle Takehiko. One night, a woman, who is dressed like a traditional oiran (high ranking courtesan), appears in front of him. The woman's name is Senka. Apparently, she just travelled across time from the Edo period to the present day and she looks completely lost. Shunsuke takes her to his uncle's house where he also stays.

Senka stays at Takehiko's house and also begins to work part-time at his cafe. Senka gets people's attention due to her appearance and behavior. Meanwhile, Shunsuke goes to the library to find information about Senka. He learns that Senka was a legendary oiran in the Edo period.

The story of the secret service team sent by the Kuomintang to escort war criminal Shi Yano from Japan to Nanjing in 1946.

The story was set during World War II when the Japanese Empire sent troops to Siam (Thailand) as part of their greater plan. Kobori, an idealistic Japanese officer set up a base camp by the Chaophraya River which is in the area of Angsumalin‘s house. He falls for her at first sight. Angsumalin, a proud Thai who despises every kind of threat to her country, sees him as a part of the Japanese Empire that deserves only hatreds. Despite his duty, Kobori wants to believe that his love will be able to find its way into her heart.