A contract killer, Seo I Do, arrives at a secluded house to take out his target, Heo Dong Hwa. Before he can finish the job, his boss unexpectedly orders him to stay put and to keep Dong Hwa captive instead. Things get messy fast when a cheerful stranger, Chu Tae Jeong, suddenly shows up. He's an old friend of Dong Hwa and was already promised a week-long stay. Their first meeting crackles with tension, and in the chaos, Tae Jeong mistakes I Do for Dong Hwa's younger brother, who supposedly left for the US years ago. I Do rides that misunderstanding, acting like the brother while quietly plotting to get Tae Jeong out of the way. His plan takes a sharp turn when he discovers Tae Jeong is actually a detective.
