Plot
Firefighter Kim Ja-hong dies in the line of duty and is escorted to the afterlife by three Grim Reapers: Hae Won-maek, Lee Deok-choon and their leader Gang-rim. They are to escort and defend Ja-hong as his guardians in seven trials within 49 days. If he passes, he will be reincarnated and his guardians will be given credit towards their own reincarnation.
In the first court, Hell of Murder, Ja-hong is tried for the death of his colleague, who was trapped beneath rubble during a fire and seemingly left to die by Ja-hong. Just as he is about to be sentenced, it is revealed that his colleague told him to prioritize saving civilians over himself. After rescuing eight others, Ja-hong attempted to go back for his colleague only to be held back as the building collapsed. The judge acquits Ja-hong.
In the second court, Hell of Indolence, Ja-hong's guardians present his selflessness and diligence. Ja-hong blurts out that he only worked for money and is about to be punished when Gang-rim interjects, stating that the money was to support his brother and ailing mother, and thus secures his second acquittal.
On the way to the Hell of Deceit, ghouls attack as the physics of Hell begins to morph. This change indicates that a member of Ja-hong's families had died and became a vengeful spirit. Gang-rim leaves the party to investigate while the remaining group proceeds. In the court, Ja-hong is accused of writing fake letters to the family of those who had died, one of whom is Ji-yeon, the daughter of his fallen colleague. Gang-rim supernaturally links with Deok-choon from the living world to defend Ja-hong, stating that he had also written fake letters to his mom to cheer her up, allowing her to focus on her health, and that the letters to Ji-Yeon, despite her understanding that her father was dead, helped her cope with her loss. The evidence is thrown out and the charges are dismissed.
Gang-rim determines that it is Ja-hong's brother Soo-hong who has become the vengeful spirit. He finds that Soo-hong has been accidentally killed while on guard duty by his partner Dong-yeon, and his death was covered up by their superior, Lieutenant Park Moo-shin. Gang-rim foils an attempt by Soo-hong to kill Dong-yeon and learns that Soo-hong's grudge was not against Ja-hong, but rather Dong-yeon and Moo-shin. Dong-yeon tips off Soo-hong's mother on the location of his body and attempts suicide. He is saved by Gang-rim at Soo-hong's request after the latter agreed to cooperate.
The trio passes through the Hells of Injustice and Betrayal without trial. In the Hell of Violence, Ja-hong is tried for beating Soo-hong when they were younger while the latter was malnourished. As Ja-hong was not forgiven, he was convicted and was about to be punished when Gang-rim instructed Deok-choon to request a combined trial at the next court, the Hell of Filial Impiety. The request is granted. Ja-hong reveals that, due to poverty, he intended to commit familicide by killing his mother but was discovered by Soo-hong. In a fit, he beat up Soo-hong and fled out of guilt, opting not to be a burden and dedicating his life to supporting them.
Gang-rim and Soo-hong arrive at the army base, only to witness the mother's shabby treatment at the hands of Park. Enraged, Soo-hong transforms back into a vengeful spirit and lashes out at the base by conjuring up a massive tornado, only stopping when he realizes how his actions are affecting Ja-hong in the afterlife.
At the Hell of Filial Impiety, Ja-hong is immediately judged by Yeomra to be guilty. He learns that on the night of his attempted murder-suicide, his mother was actually awake and had decided to allow it, knowing that she was a burden on her family. Soo-hong, with the help of Gang-rim and Won-maek, enters his mother's dream and learns that she had already forgiven Ja-hong for that night. Since sins that have been forgiven in the living world are not allowed to be judged in the afterlife, Ja-hong is allowed to reincarnate.
Afterward, Gang-rim realizes that Yeomra had been meddling with his investigation of Soo-hong. He decides to confront Yeomra directly and chooses Soo-hong as the group's final soul before their own reincarnation.
