[3] Based on BBC drama series of the same name,[4][5][6] it portrays the story of Han Jeong-hyeon (Ji Jin-hee), an agent at the National Intelligence Service, and a Human Rights lawyer, Choi Yeon-soo (Kim Hyun-joo).

The series ended on June 12, 2021 with viewer ratings of 5.2% nationwide and 6.1% in the metropolitan Seoul area.

Choi Yeon-soo (Kim Hyun-joo), his wife and a Human Rights lawyer, becomes the first Director of the Corruption Investigation Office (CIO).

[20] In July, JTBC confirmed that with the joining of Yeon Woo-jin and Han Sun-hwa the cast is completed: Ji Jin-hee, Kim Hyun-joo, Han Go-eun, Huh Joon-ho, Jung Man-sik, Kwon Hae-hyo, Park Geun-hyung, Lee Seung-joon, Lee Han-wi, Kim Soo-jin, Choi Dae-chul, Son Jong-hak, Song Young-gyu and Choi Kwang-il.

It also reunites Ji Jin-hee and Huh Joon-ho who both starred in the 2019 drama Designated Survivor: 60 Days.