Percy has to clean the stables of flesh-eating horses in order to leave the ranch. He ends up having to kill Geryon and makes peace with Eurytion.
Later that night, Eurytion lets the group stay. They learn Nico has been trying to summon his dead sister, Bianca. Together they watch as Nico tries again, and Bianca appears. She tells Nico to stop trying to bring her back to life and that she was the one telling Percy what he was doing.
The next morning they head back into the maze, following a device to lead them to Hephaestus, the god of fire and forges, in hope of being able to find Daedalus. On the way, they run into a sphinx and Annabeth has to answer riddles in order to pass. She feels like the riddles are an embaressment to her wisdom and refuses to answer, so the sphinx tries to kill them all.
When they reach Hephaestus, he asks the group to investigate one of his forges that has been being used by unknown being who dissapear anytime Hephaestus tries to catch them.
On the way to the forge, Grover discovers a path he believes leads to Pan. They decide to split up; Grover and Tyson look for Pan, Percy and Annabeth investigate the forge.
When Percy and Annabeth get to the forge, they discover creatures called telkhines have been using the forge to recreate a weapon.