Hazel meets Pasiphae who is the sorceress she's suppose to fight using The Mist.
Annabeth and Percy talk about their guilt leaving Bob and Damasen to fight for them, which will only lead to their friends' death.
Hazel manages to beat Pasiphae in the battle, so now they need to deal with Clytius who is the giant to destroys magic, and then the Doors of Death ringed, and Leo somehow threw a screw and opened the elevator.
Frank realizes that his friends are unable to do anything but stall because they can't control the undead Roman legion, but Frank steps it up and tells Jason to give him the leadership of prateor
Hecate came and stalled enough time for Frank to bring the rest of the group to help kill Clytius.
Bob tells Annabeth and Percy to go through the Doors of Death, so that he can press the button for twelve minutes for them to reach.
Frank becomes a praetor and takes charge or a undead Roman legion to fight back monsters that came from the Doors of Death.
Nico tells Cupid who he liked, and then Diocletian's scepter lay on the floor.
Nico and Jason meet an angel called Favonius, and they ask to be sent to Cupid.
The ship finally reaches the House of Hades.
Clytius dies, and Hazel and Nico shadow travel the group in order to get out of the House of Hades, and they find a visitor on the ship.
Damasen joins the party against Tartarus and his monster army along with the help of the drakon.
Frank sees a ghost from his dead family, and he gets separated from Hazel and Leo, since they are on their own journey to fight a sorceress and a giant.
Bob, Percy, and Annabeth see a drakon charging.
Percy and Annabeth meet the giant, Damasen.
Reyna talks about how peace can be made with Romans and Greeks, and the only way to do that is if she brings the Athena Parthenos with her, and Nico and Coach Hedge volunteer to help her.
Tartarus in his true form vaporizes Hyperion and Krios, and Bob and his little pet fight back in order to help Percy and Annabeth.
Percy and Annabeth see the chains from the Doors of Death and they immediately want to cut it.
Hyperion and Krios meet Bob because they are pressing the elevator button, which is how the monsters get out of Tartarus.
Reyna and her group say their good byes, so that they will be able to bring peace to Romans and Greeks, since war is about to happen.
Damasen let's Percy rest and cures him and let's Annabeth sleep with him.
Percy and Annabeth go back to their journey to find what is called the Death Mist.
Along the way, Bob encounters one of his brothers, Koios.
Jason realizes that something upsets Leo and he makes it seem that it isn't important and that they should get back to business.
Piper says "to storm or fire Gaea must fall," she infers that meaning storm or fire that one of them will sacrifice their life, since another prophecy says an oath to keep with a final breath.
Piper realizes that the only way it can be cold in July is if Khione, the goddess of snow.
Jason reaches the destination they are looking for.
She manages make the dragon head active again, but Khione's damage was done and a bomb exploded with wind, and Leo was apparently sent to an unkown place.
Percy and Annbeth reach the Doors of Death.
Leo finally found the girl he likes and then he was forced to leave.
In return, Akhlys outsmarts Annabeth and Percy because when they are in Death Mist form, they can't do anything.
Annabeth and Percy fell onto Mansion of Night, and walked through it with their eyes shut.
Calypso helps Leo build his ship only because she doesn't believe in Gaea, and she knows that he is needed in order to stop her.
Percy, Annabeth, and Bob walk around Tartarus to reach the Doors of Death entirely.
Percy manages to fight back knowing that he is the son of Poseidon and that he can control water that Akhlys created in order to destroy them.
Piper tries to do something crazy, and charmspeak an inactive head of a bronze dragon.
Lord Auster gives Jason Grace venti, which turn into horses to control in order to steer the ship into Leo's direction.
Leo's ship and Jason's group except Leo land in the lord of the South Wind's place from the bomb.
Finally Percy and Annabeth reach the person who can put the Death Mist on them.
Annabeth tries to trick Akhlys in giving the Death Mist, which she does.
Annabeth and Percy meet Nyx, and Annabeth is trying to stall or figure out a way to get to the Doors of Death without dying.
Leo learns that the girl's name is Calypso and that the island is Ogygia.
Leo landed somewhere and accidentally broke a girl's dining table.
Annabeth finds the chance and jumps with Percy into Nyx's domain, which is the only way to the Doors of Death.
Jason dreams about Reyna coming to see him.
Everyone Diocletian who was an emperor who has a staff that can be used to bring a legion of undead soldiers.
Bob helps Percy again.
Percy was cursed with gorgon's blood just like how he killed a person, so Bob wants to take Percy to a giant that might know how to cure it.
Bob learns that Percy has made him forget his memories of who he was, and doesn't protect Annabeth and Percy.
Percy obtained many curses including Annabeth by defending and killing the arai.
Hazel and Jason walk up the cliff and learn that the robber is named Sciron, and Hazel remembers what he does when he's done taking the valuables.
Hazel does what Hecates wanted her to learn, and that was create The Mist, which she does to fool Sciron.
A robber comes and asks for valuables to Leo's crew or friends.
Hazel finds Gale, a weasel that follows Hecate.
Bob sees one of his brothers reforming, and Percy tells him that Bob is a good Titan and that Hyperion is a bad Titan.
Bob, Percy, and Annabeth walk into a forest and find a bunch of demon ladies.
Percy and Annabeth finally get food from the real world from the offerings for Hermes.
Percy and Annabeth finally get to relax or sleep in Tartarus with their friend Bob who is guarding them.
Hazel gets breathes in the katobleps breathe and goes into a coma, while Frank tries to bargain with Triptolemus to try to help her.
Triptolemus accepts the deal as long as Frank can get him a python, which Frank does by killing all the katoblepones.
Percy and Annabeth get attacked by the empousai they were following.
Leo leaves Jason behind and makes homemade bombs in order to stop the dwarfs and catch them.
Percy and Annabeth climb down a massive cliff trying to catch up to the empousai.
The dwarfs steals most of the shiny things on Leo's ship and run, but Jason and Leo are trying to catch them.
The Titan kills the empousai and heals Percy and Annabeth's wounds, and says his name is Bob.
Annabeth stalls time, but the empousa Kelli didn't have enough patience, and attacked, but suddenly a Titan appeared.
Frank, Nico, and Hazel search for the owner of the book that the dwarfs stole from.
Frank, Nico, and Hazel anger monsters called katobleps.
Leo, Hazel, Nico, Jason, and Frank group in the mess hall to learn about information when suddenly dwarfs appear on the ship.
Leo has a dream about a giant who consumes all magic, and a women who wears a pendant that looks like a circular labyrinth.
Annabeth see monsters and she mouths, "Empousai, Vampires" (Riordan 55).
Percy and Annabeth walk to a river called Phlegethon, but they encounter an enemy a long the way.
Percy and Annabeth face something worse than hell itself.
Percy and Annabeth have reached Tartarus.
Hecate shows Hazel a crossroad in which she would have to choose.
Hazel meets the Goddess of magic, Hecate.
Arion sends Hazel to something that looks like a growing tornado.
Hazel's horse Arion appears as she prays to her father, Pluto, for assistance.