Following the events of Temple Crashers 2: First Blood Part 6, the deity known as The Forgotten emerges from the portal, lecturing about what's being forgotten. The monster kidnaps Breel and sends him into the Netherworld. Keene, feeling guilty for rejecting Breel, vows to enter the Netherworld to rescue him, despite Tarot telling him that getting out of the Netherworld is next to impossible. She eventually gives in, and lets Keene enter the portal using the ability to fly through the power of dreams in Keene's nightcap, while she comes up with a plan to drain the mana from the temple in order to seal the portal up.
In the Netherworld city of Pandemonium, Keene meets up an annoying demon, who wants to be taken to Earth and follows the ferret, despite Keene's protests. They later met up with a demon named Eudoant, asking where Breel might be located. Eudoant claims that Breel has likely been put to work at a factory, and later explains that work is more common in the Netherworld than torture. When they arrived at the factory, Eudoant immediately puts Keene in chains, forcing him to be put to work. Eudoant even confiscates his nightcap, rendering him powerless, and tells him to return to the apartment where they met by curfew, or else.
Meanwhile, Tarot convinces everyone to leave the temple while she and denizens of Heaven try to seal the portal to the Netherworld. When Grape asked where Max is, Tarot said that the scroll is not the same as a teleporting spell, and Max is seen being pampered by Keene's butler, Jeeves. As the adventurers prepare to leave, Dallas returns. Realizing Dallas is cosplaying as Scotty from Star Trek, the others beg him to beam them up in order to escape.