Yoo Si-jin (Song Joong-ki) is the captain of a South Korean Special Forces unit. He and his friend Master Sergeant Seo Dae-young (Jin Goo) are off-duty when they witness a young man stealing a motorcycle and apprehend him. The thief, Kim Gi-bum (Kim Min-seok), is injured during the chase and therefore sent to the hospital. Dae-young realises his cell phone was stolen by the thief and goes to the hospital with Si-jin to retrieve it.Reunion: The Sound of the Providence Season 1 Download.
In the emergency room, Si-jin meets Dr Kang Mo-yeon (Song Hye-kyo) for the first time and is instantly attracted to her. Mo-Yeon mistakenly assumes Si-jin is part of the thief’s criminal gang after hearing him being addressed as “Big Boss”, which is his call sign by Seo Dae-young. He proves his identity with the help of army surgeon Yoon Myung-Ju (Kim Ji-won) who did their housemanship together.
Si-jin and Mo-Yeon begin to date, but due to Si-jin often being called in for duty, their dates are often interrupted halfway. Si-jin receives his orders to be deployed on a peacekeeping mission in the fictional war-torn country of Uruk. Meanwhile, Mo-Yeon is upset because she found out that she had been passed over for a professorship favouring a less-capable colleague who had familial connections to the hospital management. When Si-jin returns and meets Mo-Yeon again, she directly asks him to explain his sudden disappearances and job. Still, he cannot go into too much detail due to the highly classified nature of his assignments. They talk about their views on life and realise how different they are. Si-jin, as a soldier, kills to protect lives while Mo-Yeon, as a doctor, honours the Hippocratic Oath and tries to save lives. Due to their philosophical differences, they agree to part ways. Dae-young, on the other hand, faces a dilemma on whether to continue his relationship with Myung-Ju or risk being forced out of the army for breaking fraternisation rules set by Myung-Ju father, a three-star general and commander of the Special Forces.