Descendants of the Sun is a 2016 South Korean television series, starring Song Joong-ki, Song Hye-kyo, Jin Goo, and Kim Ji-won.
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.
In the emergency room, Si-jin meets Dr Kang Mo-yeon (Song Hye-kyo) for the first time and is instantly attracted to him. Dr Kang 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)
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 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 disappearance and job. Si-jin cannot go into much details due to the classified nature of his assignments. They talk about their views on life and realise how different they are, as a soldier who kills to protect lives while Mo-Yeon, as a doctor, who honours the medical Oath to save lives.
Due to their 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 rules set by Myung-Ju father, a three-star general and commander of the Special Forces.
Eight months later, Mo-Yeon rejects the romantic advances of the hospital director as a result, is assigned against her will to lead a team of medical volunteers to Uruk as revenge for her turning down the hospital director.
At Uruk, Si-jin and Mo-yeon reunite and both gain a deeper insight into one’s jobs as their respective teams endure an earthquake and a viral epidemic. Dealing with a warlord who once fought by Si-jin’s side but now takes advantage of the corrupt government of Uruk to make money off human trafficking.