The House of Hades

The mess hall walls are enchanted to show scenes of Camp Half-Blood, which makes Leo feel homesick. Jason, Hazel, Frank, and Nico round out the group. Piper and Coach Hedge guard the deck. Nico communed with the dead about the House of Hades. The ghost of a priest of Hecate spoke to Nico about Hecate’s foe in the first giant war, Clytius, waiting for them. Nico’s ghost said fire is Clytius’s weakness and everyone expects Leo and his fire magic to help, but Leo can’t shake the fear from his dream. The ship lurches, and the enchanted walls show two individuals stealing things while Piper and Coach Hedge are immobilized with duct tape. Leo runs to stop them.

Hazel stays to help Nico, who hit his head, while Jason and Frank go with Leo. The two thieves use a magic flash-bang grenade to immobilize Leo, Jason, and Frank and steal Leo’s tool belt before escaping. Frank, who shape-shifted into a gorilla, lies unconscious while Jason uses his wind power to fly him and Leo to Bologna to look for the Kerkopes, brothers that Zeus turned into monkeys. Leo climbs a statue of Neptune and finds the one of them at a nearby table while the other sits on top of the statue with Leo’s toolbelt. He introduces himself as Akmon and the one at the table as Passalos. Jason lunges at Passalos, but he jumps on Jason and steals Leo’s zipper, so his pants fall down. Leo summons fire and Jason summons thunder, but the brothers activate the statue. Leo ducks so the magical net misses him but hangs Jason upside down from the statue. The brothers run away, and Jason tells Leo to go.

Leo follows the brothers until they disappear up a tower. He buys stuff with chemicals to make explosives, a laundry cord for a belt, and some junk food at a grocery store. In a doorway, he makes the explosives and looks for Jason, who doesn’t show up. Leo finds the brothers in the top room with their treasure trove. Leo holds out his grocery bag. When they come close, Leo activates his explosives which temporarily blind them, grabs his tool belt, and uses a bungee cord inside to tie them up.

Akmon and Passalos try to bargain with Leo as Jason flies in the window. Jason and Leo gather their stuff. Leo finds a damaged bronze navigation device the brothers say was Odysseus’s last invention but needs a crystal. He also finds a book they stole from a god in Venice, which must have been what Hecate meant for them to find in Bologna. Jason threatens the brothers to give them the address. Akmon and Passalos beg not to be killed. Leo feels bad about killing them and makes a deal with them to set them free if they will harass the Romans marching on Camp Half-Blood.

Percy and Annabeth stay far enough behind Kelli and her crew to avoid being seen. They periodically stop and drink firewater from the River Phlegethon to keep themselves healthy. The empousai disappear over a cliff and climb toward ground pocked with bubbles that birth monsters. The new monsters head toward black fog where the Phlegethon meets another river, which Percy assumes obscures the Doors of Death. Percy doesn’t see the empousai anymore, but now they know where to go.

Percy is so focused on climbing down that he doesn’t realize how tired Annabeth is until she asks to rest. He feels guilty and pulls her into his arms on a ledge. Annabeth tries to cheer Percy up by reminding him they could’ve landed in the River Lethe, which wipes memories. That makes Percy think about his amnesia and how he wiped the memory of the Titan Iapetus. Percy tells Annabeth he renamed Iapetus Bob and left him in Hades’s palace. They climb to the bottom, and Percy realizes he's standing on skin and feels a dark presence. Percy sees movement and realizes he doesn’t know where the empousai are. He draws his sword as they encircle him and Annabeth. Kelli announces she’s thrilled to destroy Percy.

Kelli recognizes Annabeth from stabbing her in the back to save Percy. Percy and Annabeth stall by talking and get Kelli to kill one empousai, but the rest prepare to attack. Percy attacks Kelli and kills an empousai, but Kelli charges Annabeth. One empousai grabs Percy’s arm, and the other jumps on his back. Percy tries to get to Annabeth, who evades Kelli by throwing rocks. Percy is startled by Annabeth’s scream when Kelli throws her to the floor. Percy stumbles toward Annabeth, but the vampires bite him, and he falls to his knees. Kelli and her friends go for the kill when a Titan drops onto the battlefield.

Bob the Titan in a janitor's uniform tramples Kelli to dust and uses a spearhead from his broom to kill the last two empousai. Bob says his friend Percy called him, so he left his janitor job in Hades’s palace and came to help. He heals Percy’s and Annabeth’s wounds by touching them. Bob says he will lead them to a safe place because monsters are coming to find them.