Joon, a former elite assassin for the National Intelligence Service, traded in his lethal skills for a quiet life as a struggling webcomic artist. After faking his death to pursue his passion, he now lives a peaceful existence with his wife, Mi-Na, and their daughter.

However, a drunken night leads to a fateful mistake. In a moment of impulsive creativity, Joon draws a comic strip revealing his dark past as a hitman. The comic, filled with classified information, is accidentally uploaded online, putting his family and himself in grave danger.

As the consequences of his actions begin to unfold, Joon must confront his past and the enemies he left behind. With the clock ticking, he must protect his loved ones and unravel the mystery surrounding the leak of his secret identity.