There are a total of seven trials Kim Ja-Hong (played by Cha Tae-hyun) visits during the film. They are (in order): Hell of Murder (judges if your past actions influenced someone's death) Hell of Indolence (judges if the noble life given to the subject was wasted) Hell of Deceit (judges the lies one has told in one's life) Hell of Injustice (judges refusal to help those in need, especially for selfish gains) Hell of Betrayal (judges the cold-hearted who betrayed faith or trust) Hell of Violence (judges any physical attacks on others) Hell of Filial Impiety (judges dishonor or disrespect of one's parents, elders, and ancestors)
The VFX works made for this film by the Dexter studios was this film director Kim Yong-Hwa's own VFX house.
The movie is an adaptation of the well-known webtoon called, "Along With the Gods"
The order of the trials is determined by the King of the Underworld, Yeomra (played by Lee Jung-jae), who judges each individual's sins from lightest to heaviest.
The film is inspired by the Korean Joseon dynasty Buddhist paintings and early Buddhist scriptures of the "Ten Kings of Hell". In the early Buddhism concepts, the Ten Kings of Hell serve as magistrates of each of the ten courts of the underworld to determine the fate of the deceased including the type and severity of punishment and the course of their cycle of rebirth. On the 49th day after death, the soul of the deceased comes before the seventh king and may be reborn, depending on his or her actions in this world.