At the top of his class, Won Ryu-hwan ranks as one of the elite soldiers in the North Korean military. Due to his outstanding talent, Ryu-hwan has been selected for the 5446 Project: a mission to infiltrate the South and gather information on its inhabitants. However, upon deployment, he is utterly disappointed to find out what this truly entails—he must disguise himself as a village bum in Seoul. Fiercely loyal to his country nonetheless, Ryu-hwan dutifully commits to this humiliating role and successfully establishes himself as Bang Dong-gu, the bottom of the bottom-rung.

Two years later, Ryu-hwan has persevered, despite no sign of the mission progressing. Yet the arrival of Lieutenants Rhee Hae-rang and Rhee Hae-jin, two fellow spies from his division, heralds the winds of change to their mission. As they settle in the town, developments between the North and South threaten to alter the status quo. With their loyalties to each other and their home being tested, the three men must decide what is most important to them: their devotion to their country or their very own lives.