Korea, 1645 - Joseon Dynasty: a partially blind and gifted acupuncturist, Gyeong-su, is invited to work alongside the royal physician in the palace of King Injo, just before the crown prince Sohyeon returns after having been held captive by the Qing Dynasty. Prince Sohyeon and his father begin to differ in opinion on the future direction of their dynasty, leading King Injo to suffer from severe anxiety and paranoia. One night, Gyeong-su witnesses prince Sohyeon's death. Disbelieved as a witness on account of his blindness, Gyeong-su must struggle to reveal the truth while not falling prey to the power-hungry conspirators of the palace.

Follows Rim Chul-ryung heading back to South Korea in pursuit of a brutal and secret criminal organization. He teams up again with Kang Jin-tae, who volunteers to work with the North Korean in order to get back on the investigation team after a mistake landed him in the cyber crime department.