The protagonist of the movie is a North Korean fisherman, Nam Chul-woo, who accidentally drifts into South Korean waters while fishing. Initially, he tries to return home but is unable to do so due to a series of events. He then accepts an offer to work as a spy for South Korea in exchange for his family's safety and a substantial amount of money.
The South Korean military officer in charge of Nam's training is named Kang Jeong-hak. Kang is an ambitious and patriotic officer who sees Nam as a valuable asset in the ongoing conflict between North and South Korea. He trains Nam in the art of espionage and teaches him how to blend in with South Korean society.
As Nam begins his new life as a spy, he struggles to deal with the guilt of betraying his homeland and his people. He also faces numerous challenges, including the constant threat of being caught by North Korean agents, as well as the everyday difficulties of adapting to life in a new country.
As Nam grows more accustomed to his new life, he starts to unravel a dangerous conspiracy involving a powerful North Korean official and a group of South Korean traitors. This puts him in grave danger, and he must use all of his training and ingenuity to stay alive and complete his mission.
In the end, Nam emerges as a hero, having risked everything to protect both North and South Korea from a dangerous threat. The movie ends on a hopeful note, as Nam finds a new sense of purpose and belonging in his adopted country.
