Shi-Jin (Song Joong-Ki) is the captain of the special forces. He catches a motorcycle thief with Sergeant Major Dae-Young (Jin Goo). The thief is injured during his capture and is sent to the hospital. Dae-Young realises his cellphone was stolen by the thief and goes to the hospital to retrieve his cellphone. In the emergency room, Shi-Jin meets Dr. Mo-Yeon (Song Hye-Kyo) for the first time. He falls in love with her immediately. Mo-Yeon mistakenly assumes Shi-Jin is part of thief’s criminal gang. He proves to her that he is a soldier with the help of army doctor Myeong-Joo (Kim Ji-Won). Shi-Jin and Mo-Yeon begin to date, but due to their jobs their dates don’t go well. Shi-Jin takes an order to lead his soldiers on a peacekeeping mission to the country of Uruk. Meanwhile, Mo-Yeon becomes upset that she fails to become a professor due to a colleague’s privileged background. When Shi-Jin and Mo-Yeon meet again, they talk about their views on life and realise how different they are. Shi-Jin, as a soldier, kills to protect lives and Mo-Yeon, as a doctor, tries to save all lives. They say their goodbyes. Eight months later, Mo-Yeon rebuffs the sexual advances of hospital chairman Suk-Won (Tae In-Ho) and as retribution is assigned to lead a medical team in Uruk. There, Shi-Jin and Mo-Yeon meet again.