Jae-sung Lee Joon is an aspiring actor who has hit rock bottom and contemplates suicide. After a harsh insult from his landlady, he seeks a moment of relief in a public sauna, hoping to wash away the sting of failure. There, a different life collides with his when Hyung-wook Yoo Hai-jin, a notorious assassin, is in the sauna after finishing a target. In a chaotic moment, Hyung-wook slips on a soap Jae-sung drops and passes out. Seeing Hyung-wook's ostentatious, almost luxurious look, Jae-sung makes a impulsive decision: he swaps lockers, steals the other man's car and money, and disappears into the night. Guilt gnaws at him, and he later tries to return everything to the stranger, only to find Hyung-wook barely conscious in the emergency room. When Jae-sung is about to leave, Hyung-wook grabs him, but Hyung-wook's memory is so fuzzy that he can't recall the encounter, and Jae-sung slips away without saying a word.
While Jae-sung enjoys the borrowed wealth and the gleam of a new life, Hyung-wook struggles to piece his own identity back together. He cannot pay his hospital bill, and a paramedic named Lina steps in to help by paying the bill, on the condition that he repay her later. As it turns out, Hyung-wook's hands-on talent with a knife helps him land the role as the restaurant’s main chef, drawing in curious customers with his practiced, precise technique. The story deepens when he discovers a calendar date and a location that hint at a life he has yet to live: a future as an actor who would appear in a gangster-themed TV show, even as the original life he stole haunts him.
Despite starting awkwardly, Hyung-wook thrives in action scenes, leveraging real-life skill to boost the show's intensity. With Lina’s support, his role grows, and the on-screen presence becomes more significant as the series progresses. The two begin to develop genuine feelings for each other, complicating the plan to escape their pasts. Meanwhile, in Hyung-wook’s apartment, Jae-sung discovers a secret room and grows suspicious that Hyung-wook is an undercover cop protecting a witness named Eun-joo Lim Ji-yeon, who lives in the same building. Jae-sung starts quietly watching Eun-joo and, over time, finds himself drawn to her.
One day, Jae-sung answers a phone call for Hyung-wook and meets with businessmen who press him on why Eun-joo is still alive. He realizes that Hyung-wook is not a traditional assassin but someone who has been helping to give new lives to assassination victims by faking their deaths and sharing the profits. The trio—Hyung-wook, Jae-sung, and Eun-joo—devise a plan to disappear and start anew. Hyung-wook tells Lina that they cannot be together and leaves. She follows him to a place where they intend to fake their own deaths in front of the people who hired Hyung-wook, and Lina’s unexpected interference nearly sabotages the plan. The businessmen believe they are dead and walk away. In the end, Hyung-wook reveals his true identity and apologizes. Lina, unsure what to do, accompanies him to the TV set to finish the final scene. On the set, Hyung-wook improvises new lines and confesses his feelings to Lina, who accepts him. Jae-sung and Hyung-wook then star together in a new TV show.
