As the cabal recovers from the battles for Norna and the death of Cob, they decide that something has to done to replace Cob as guardian of the city. Following up on the spirit of Rota's advice, they plot to retrieve Rota's ghost and convince it to perform the necessary ceremony to turn Ellsworth from a ghost in the architecture into a true spirit of the city. In preparation for their journey into the Underworld, Adele consults with Rota's spirit on the dangers they will face and where to look. Colt meanwhile gathers supplies for the journey. Valkyrie and Mammon collect items to use as bribes with the ghosts to get information from them. They decide against involving the neophyte mage Norna, however.
Upon nightfall in the heat of the summer, Adele opens the gateway in the graveyard behind the house. Cool air rises up from a series of stairs leading down into an open grave. Adele skips into darkness of the Underworld, while the others cautiously follow. Beneath they navigate the tight earthen tunnels, swarming with the recently dead. Seeking the ghost of Rota, they begin to question the deceased. They find a fat ghost by the name of Carol Snyder, who they bribe with a bag of chips. She has never heard of Rota but points them to a more well traveled ghost further down in the tunnels. They descend and find Gary Darling, a dead alcoholic lounging on a pile of rib cages. Mammon charms him with some alcohol and he gives them directions further down where the old man passed many years before.
The tunnels lead to into a a familiar looking structure. Past a metal door, they find bland, eggshell-white walls with shiny black countertops and matte black fixtures. Valkyrie recognizes the severe 1980s design style. This is the Burgess House. The steel door slams shut as several charred ghosts drift into the room. Adele recognizes them as Anna's sacrifices from the warehouse fire, the ones she cast into the Underworld. She tries to control them but they resist her magics. Valkyrie creates a bright blade of fire while Colt and Mammon ready their weapons. As Colt shoots at the ghosts, a table is hurled telekinetically at Adele. Mammon punches a ghost with his dagger and Valkyrie slices another open with her sword, sending it screaming into a wall. Adele pulls out her bow and lets an arrow fly. The ghosts retaliate by filling Valkyrie's eyes with smoke, while Hope causes one to fade away with a well placed arrow. As Colt's bullets continue to hammer the specters, a heavy sculpture slams into the back of Valkyrie's head. Mammon defeats his ghost and Valkyrie seeing double, manages to injure the final spirit. Adele cries "Show yourself" as Hope takes down the final ghost. As they seek out Burgess himself, Colt prepares a spell. Valkyrie fights off an attempt to possess her and Mammon points out the evil ghost's location. Valkyrie heads into the room he is hiding in and stabs him but his tough stony skin wards off most of the attack. Adele lashes out with death magic while Hope looks for a good shot. Colt completes his spell, causes the bruises on Valkyrie's body to fade. Burgess punches her then with incredible force. Valkyrie retaliates as Adele and Colt shoot at the cracks appearing in his skin. Burgess attempts to crush Adele telekinetically while Mammon attacks the building directly, weakening Burgess. The cabal concentrate their attacks, chipping away at Burgess and his house. Weakened the evil ghost lashes out a final time, bludgeoning Valkyrie into the wall. But she pushes off the wall stabbing him through the chest with her blade of fire, defeating him. As the house collapses, they flee further deeper into the Underworld.
They travel deeper, following Darling's instructions. Along the way they encounter the ghost of an old woman, busily cleaning her section of the Underworld. After a short chat she points them further on. They pass tunnels crawling with inch thick worms and dripping with muddy earth. Eventually the rough dirt gives way to cinder blocks and an open hidden door. Inside is an opulent underground speak easy. On stage a woman croons in a tattered and faded dress, more red from her blood than its original color. A large crowd of ghosts fills the room where they engage in debauchery without joy or lust. A group of gangsters play cards with the victor earning everything the loser has but there is no joy in his eyes nor fear in the victim. A door opens out to a second exit where a pair of thugs beat up a third ghost. His limbs are broken but mend in seconds to be broken anew. At the bar a trio of ghosts drink themselves into oblivion.
Valkyrie approaches the gamblers, striking up a conversation with an old ghost named Jack. At the offer of some food, the western card shark agrees to gamble, wagering his knowledge against the gift basket. Mammon decides to play him but despite his magically boosted skills and cheats, he loses. Mammon challenges him to another game, double or nothing. In the second match, the crafty mage wins. Jack tells them Rota passed through over a decade ago, heading to the river of blood in search of some secret. He also tells them of a shortcut, through an ancient gateway, but warns them that one of them will have to leave a portion of themselves behind as collateral.
They quickly find the gateway. On the wall next to the gate is a gore coated hook adorned with several limbs. A worn metal plaque beside it says:
A Toll must be paid to cross into the Lower Mysteries,
A Toll in Flesh and Blood
Colt spears his arm onto the hook. His arm comes loose and is replaced by a ghostly version of itself. The gate opens and the cabal, disturbed, pushes on.
Past the gate they descend into a large chamber filled with plague dead. The air is thick with a strange fishy smell. The ghosts, many of them children, seem dehydrated, begging for water. As the cabal questions how so many died, Valkyrie recalls a bit of urban legend about a Cholera outbreak in 1885 that killed tens of thousands. They decide to lead a few of the ghosts away from the horde. Bribing them with fresh water, they learn the children's names: Jim Adams (age 10), Edward Brown (age 8), Alice Dodd (age 11), and Sue Perkins (age 7). The mages ask about Rota as well as how to pay the ferryman. The children are able to answer the second question, pointing out that he takes secrets, personal items, and blood in trade.
They push through the crowds and soon arrive at the river, its banks obscured by reeds. A think metallic smell fills the air. Pushing through the assembled hordes of the dead, they search for Rota. They talk to the chatty Ginger Hichens, who choked on fish bone and complains about her failure of a husband. From her they learn that Rota passed over the river in search of a realm known as the Empty Chapel. They approach the withered native american ferryman and his canoe and pay him a pile of silver pieces to cross the river.
On the other side they quickly take a wrong turn, ending up at a dead end. The chamber is dark and dripping blood from the ceiling. Inside 13 figures stand like statues, slowly drinking the blood that falls. Questioning one, they see it has glowing red eyes. It tells them that they are waiting for awakening of the Antediluvian. Mammon asks how soon will it awaken. The creature's reply is that the old one will awaken in a full turn of the seasons.
They quickly retrace their steps, leaving behind the vampires. They get directions from an old man with a large pile of books about him. His directions lead them deeper into the Underworld through a series of tight tunnels. They squeeze through, avoiding a hungry ghost crawling after them in the dark confines. Beyond, the tunnels expand into vast chambers where flocks of birds and bats swarm high above. They question an eyeless ghost wearing clothing made from human skin about directions and the creatures, learning that they are psychopomps, that supposedly guide the dead into the depths of the Underworld.
Finally they come to the massive set of charred timber doors that mark the entrance to the Empty Chapel. Over the doors are written the two Old Laws of this realm:
Thou Shalt Not Call on the the Supernal Heavens
All Must Partake of Worship
Written on the door in chalk are some odd hebrew characters warning of something from before the flood. The cabal enters. Inside the roof rises into a vast cathedral decorated in the symbols of a dozen religions. Most prominently are the signs of the Jesuit Order: the sun pattern, three nails, and Jesus's name. The church itself is ornate, decorated in gold, statuary, and religious symbols. Hundreds of ghosts line the pews filling the hall with a cacophony of different prayers. They sing until they are hoarse, bow their heads to ground until they bleed, and starve themselves into human skeletons. Over all of this, the singing of a choir can be heard. The mages instantly notice that the air is charged with the energies of the Supernal. Looking further in they can see the pulpit is empty but behind it is an alter with a bowl into which drips the blood of a crucified creature on an inverted cross. The humanoid figure is withered and gray, dressed only in a single decaying cloth.
Once inside Adele and the others make an attempt to pray, as well as lighting prayer candles. A colonial era ghost belonging to the Adamantite Arrow however informs them, "That's not the kind of prayer they are looking for." He introduces himself as Dilios and informs that he knows where Rota is. He also warns them of the dangers of the Empty Chapel's communion. You must drink the blood from the creature hanging form the cross. The substance is addictive and leads one away from the Supernal. Dilios tries to warn ghost mages who come here to leave, but many ignore his warning. He mentions a mage who fled even before he could talk to him, panicking upon seeing the corpse. They ask if he knows someone who can translate Hebrew and Dilios points out Titus. Mammon consults with him, finding him distracted and looking for his next hit of blood. He is able to learn that it is a warning about the Antediluvian. They find and talk to Rota just as communion begins. While in line they try but fail to convince him to leave with them, finding Rota to be fairly addicted and harsh in person. In the end they do convince him to examine Adele's aura to see if she really is his student. They all also are forced to drink the Antediluvian blood which they find amazingly delicious. After communion Rota and the cabal leave the chapel and he quickly realizes the truth. With his goal of ascension in sight, he pushes through the years of addiction, and joins them as they head back to the surface.
Returning to the river of blood, they are forced to pay the ferryman again. Rota and Hope each trade him a secret, while Adele gives him a bracelet given to her by Miguel. Mammon trades him his magic tool, a brass mirror, and Valkyrie gives him some earings given to her by her son. Colt feeds the withered spirit his blood. They cross the river without incident and quickly climb back up toward the real world. Along the way they find a human body lying in a chamber guarded by an assortment of psychopomps. He seems to have died recently of a broken neck, likely caused by a fall. He has no ID, but they take some notes he had on him and press on to the gate. At the gate Adele makes herself Rota's new anchor to tie him to the living realm.
They return to the world with the sun shining down, their quest complete. A few nights later, Rota using a potent ritual aided by Decima, Babbage, Virgil and Adele, makes Ellsworth into the guardian Giest of Chicago. Athaliah, Dearborn and Cornerstone join as observers. The transformed ghost's power begins to move throughout the city, healing the infrastructure and sealing the forces beneath it.