Seo Do-young

Han Dong-su, a lawyer going through hard times. After nearly losing his license due to an unfair accusation, he was forced to leave a major law firm. Now he has to scrape by on petty cases, in particular providing legal aid to inmates at the local prison, hoping that one of them will take him up on his services. His younger half-brother, Han Beom-jae, works at a used computer shop and helps his brother find clients. One day, Dong-su is approached by an inmate named Seo Do-young — a former baseball player who is the number-two man in one of the crime syndicates, "Yeosung." He is described as a man with a handsome face that conceals unpredictable cruelty. For a substantial fee, Do-young asks the lawyer to keep an eye on his girlfriend while he is in prison. Dong-su, facing financial hardship, agrees to the task despite his inner misgivings. Taking on what seems like a simple jealousy case, Dong-su has no idea that a far more dangerous reality lies behind it. As he carries out the assignment, he begins to get drawn into a world of gangster intrigues and power struggles.

Lawyer Han Dong-su and his brother Beom-jae continue to tail Do-young's girlfriend, Park Chae-i, but find nothing suspicious. However, instead of being reassured, Do-young flies into a rage. In prison, he threatens Dong-su, reminding him of his family, and demands that he find some proof of infidelity before his release, which is due in just a few days.
Realizing that something is off, the brothers decide to dig deeper. Their investigation leads to a shocking discovery: a conspiracy is brewing inside Do-young's gang. It turns out his girlfriend is cheating on him with one of the gang members, and together they are planning to kill Do-young.

To obtain evidence, Dong-su and Beom-jae break into Chae-i's house and install hidden cameras. Inside the house, they find something unexpected — a person hooked up to life-support machines, who, as it later turns out, is the real boss of the organization, the one Dong-su's former colleague had mentioned.
Dong-su realizes he has gotten entangled in a power struggle within the criminal underworld.

The following evening, Dong-su sneaks into Chae-i's house while she is out, intending to retrieve the video cameras with the evidence, when suddenly...

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