Heo Im (Kim Nam-gil) is a Joseon doctor of Traditional Korean medicine, specializing in acupuncture.

He worked at a clinic for the poor during the daytime, and earned a fortune by making secret visits to nobles and high-ranking officials' houses at night.

After gaining notoriety for his great skills, he was tasked to help treat the king's migraines.

He was eventually cornered into a river and fatally shot by arrows, and fell to his supposed death.

Dazed, lost and confused, he runs into Choi Yeon-kyung (Kim Ah-joong), a cardiothoracic fellow surgeon at Shinhae Hospital, and begins an unlikely relationship across time and space.