Based on the events occurring around "Route 1", which lies between Seoul and Pyongyang. The story about Officer Lee Jang Woo (So Ji Sub) who finds himself in a war that he is not prepared for in order to protect Soo Yeon (Kim Ha Neul), the woman he has known and loved since youth. However, he is able to put it past him and he displays extraordinary survival skills, friendship, cooperation and ideology under brutal war conditions. Soo Yeon awaits Jang Woo's return, but eventually gets engaged to Tae Ho (Yoon Kye Sang). When Jang Woo returns alive, however, Tae Ho discovers Jang Woo and Soo Yeon's unbreakable bond and feels betrayed.