This film follows the story of three sons as they investigate the murder of their father, the late Director Tak Myung-hwan, a researcher of cults, and the forces behind it. Tak Myung-hwan, the director of 'Modern Religion,' was a so-called 'cult hunter' who dedicated his life to fighting heresies, exposing the corruption of cults such as JMS, Shincheonji, Yeongsaenggyo, Unification Church, and the Gospel Baptist Church. He is also well-known as the real-life inspiration for the character Pastor Park in the film 'Svaha: The Sixth Finger,' directed by Jang Jae-hyun and starring Lee Jung-jae.