A deadly disease takes over the entire world. Amid the chaos, a young doctor joins forces with an experienced soldier…

People say a soldier and a doctor will make a good couple because both works as a frontliner to the country. Soldier gets hurt in a war and a doctor will cure them. Doctor helps people and soldier protecting people.

It was supposed to be a café love story, but they never got to meet a second time until four years passed them by. As they come face to face once again, Jeongyeon is now a lieutenant commander in the special forces and Nayeon is the secretary to the CEO of YeSsang Enterprises, a major medical technology provider in Seoul. Amid top-secret missions and emergency surgeries, how will they bridge their gap?