"I love it when you talk medical to me" Lee Y/N, a John Hopkins graduate, who's back in Korea to begin her life as a doctor joins Asan Medical Centre only to find out that her Ex, Dr Kim Seokjin, from the University, is now her chief resident at work. Memories rush in, but after their separation, the only thing she wants to do is to ignore him, but life is a roller-coaster that turns into a water slide, What happens when she also starts to fall in love with his best friend, Dr Kim Namjoon? Will she choose Seokjin or Namjoon?