Deep in South Korea. Kim Kang Heon is the chairman of Woo One Group (or Woowon Group), a large conglomerate officially engaged in business and urban development. However, behind the company's legitimate image, this group has deep roots in the criminal underworld and is involved in various illegal activities, ranging from corruption and intimidation to organized violence. Kim Kang Heon uses his wealth, power, and network of subordinates to control much of Woowon and influence government officials and law enforcement.

His eldest son, Kim Sang Hyuk, also wields significant influence within the organization and often acts as his father's right-hand man in matters involving violence and revenge.

The family is on a revenge mission for the death of Kim Sang Hyuk's younger brother, caused by the son of a judge. Song Pan Ho, a judge known for his honesty and upholding justice, learns that his son, Song Ho Young, was involved in a hit-and-run accident that killed the son of a powerful crime boss. Initially, he wanted his son to turn himself in, but the fear of losing him made him decide to cover up the incident.

On the other hand, a high school student at Kanghak High School, Guest, was just an ordinary high school student who one night received a call from an unknown person, offering him a job that was quite life-threatening.

To be Kim Sang Hyuk's butler. However, Guest accepted the offer and worked the next night. He stood by Kim Sang Hyuk as he bathed in his penthouse while making a phone call to someone Guest didn't know, and also drank red wine.