The episode unfolds with a narration by Lilith. In the beginning, Lilith had been wandering the wilderness for months, if not years when everything outside of the Garden of Eden was still a stony wasteland. She encountered Satan, whom she describes as a beautiful angelic man with two wounds on his back. He lifted her up and in return, she healed the wounds caused by the loss of his angel wings. For she was not only the first woman, but also the first witch, Lilith, and he Lucifer, the Morningstar, soon to be their Dark Lord. She was his handmaiden and he was her master.
In the present, the Dark Lord emerges from Hell into the Greendale Wood in his true form. Meanwhile, Sabrina returns home with Nick and Ambrose. Zelda asks her where she has been all night, asking her if she knows about the troubles they are in. Sabrina warns Zelda and Hilda about the events about to unfold in Greendale. "Ms. Wardwell" manipulated her into fulfilling a prophecy meant to bring about the end of the world. Because of her, the Dark Lord has assumed his true form and is in Greendale. Moreover, the Gates of Hell are about to open, releasing the hordes of Hell.
According to the prophecy Nick found, the Dark Lord's plan is to enslave the tribes of mortal and witch-kind and to rule over everything with his demon army. Ambrose adds that Sabrina created a mandrake that's absorbed all of her witch powers. Sabrina adds that that is not even the worst of it. What's worse than Sabrina being mortal, Zelda scoffs. Ambrose reponses that Sabrina is meant to rule by the Dark Lord’s side as his Queen. Zelda objects vehemently to her niece being his child bride because Sabrina is too young and vows to stand against the Dark Lord for her family.
Working together, the Spellmans and Nick build a protection around the house. Nick tells Sabrina that they need to find where in Greendale the Dark Lord is. Shortly after, Harvey, Roz and Theo arrive. They ask Sabrina if she's the real Sabrina or "The Sabrina who tried to kill us and turn us into vegetables". Sabrina reassures her friends that she is the real Sabrina and not the doppelgänger. Harvey demands to know what is going on. Sabrina explains that the Dark Lord is in Greendale and that he wants to jumpstart the Apocalypse by opening the Gates of Hell which are also in Greendale. Harvey deduces that the Gates of Hell are in the mines and offers to help. Nick advises him to sit this out but Harvey convinces Sabrina to let him and her other friends help. Despite Nick advising against, Sabrina tells her friends to locate the gate and find a way to keep the Dark Lord's forces from opening the doorway. Harvey suggests dynamite and Sabrina approves of the plan. From the Mortuary, Zelda calls Sabrina inside, but not before Sabrina kisses Nick goodbye telling him to be careful and stick to the shadows.
At the Academy of Unseen Arts, Prudence approaches Dorcas and Agatha for their help. They reject being called sisters, seeing as they don't share the Blackwood name. When Prudence reveals to them of her plan to kill Faustus Blackwood, she gains their attention. How they will do it since he won’t let them get close, they ask. Prudence replies that they won't need to and shows a red ribbon.
At Dorian's Gray Room, Dorian Gray is visited by a naked Lucifer. Gray doesn't recognize the Dark Lord at first but takes a liking towards him. The Dark Lord reminds Dorian of their bargain; eternal youth in exchange for his soul. Dorian is taken aback upon realization, apologizing to the Dark Lord for his poor manners. As the Dark Lord proceeds to demand Lilith's whereabouts, she surfaces. The Dark Lord expresses surprise that she did not greet him in his angelic form. Lilith claims she's been busy preparing the way. Nevertheless, she doesn't seem ecstatic to see him and the Dark Lord notices this too. Lilith is unhappy that Sabrina is inheriting the Throne and Crown that was promised to her. But it is not her turn yet. Lilith sips her drink, mumbling "not ever". The Dark Lord promises that she will lead the armies of Hell when the gates open. Lilith is not satisfied, however, and asks why he chose her of all people. Avoiding her question, the Dark Lord claims he is bored with her self-pity and orders her to bring Sabrina Spellman immediately. Lilith fearfully obeys, leaving him to go do his bidding. Meanwhile, the Dark Lord will be attending to certain wayward members of his flock.
Back at the Academy, the Weird Sisters sing and dance around a statue of Father Blackwood while holding the red cloth in a triangle. Meanwhile, in his office, Blackwood starts to bleed from his nose. Just then, Melvin enters Blackwood's office to inform him that the Dark Lord has returned in his angelic form and awaits his presence at Dorian Gray's Room. Blackwood thinks the blood to be a sign. He tells Prudence that the Dark Lord has summoned him and that she must attend him.
Back at the Spellman Mortuary, Zelda is perplexed because the Satanic Bible does not speak of the world being destroyed and remade into a Hell on Earth. However, it makes perfect sense for Sabrina. The Dark Lord wanted the Churches of Darkness to serve him so he kept the truth from them. But this time it's not just Greendale at stake, it's the world. Zelda vows to protect Sabrina at all costs, as she may be the centerpiece to all of the Dark Lord's plans. This makes Sabrina think her father knew. Zelda takes offense about Sabrina's insinuation of her father conniving with the Dark Lord. The Dark Lord needed her because she was a girl who represented the two tribes, Sabrina explains. He wants to rule over witches and humankind, so why not have her father marry her mortal mother? Even if that is a possibility, Zelda vows to not let Sabrina be the Dark Lord's Queen. Ambrose returns with the Demonicon, announcing that he has found something useful; the Melmoth spell. It involves carving a sigil into her soul, which will keep her hidden from the Dark Lord provided she's constantly moving.
Lilith warns them that nobody can run from the Dark Lord, as she's experienced that herself. Startled by her presence, they all turn to her as Sabrina explains how "Ms. Wardwell" has been plotting against her with the Dark Lord. When asked how she got past the onions, Lilith explains that she does not have the same aversion to onions that the Dark Lord has. Lilith tells Sabrina to come along but her aunts and Ambrose assume a defensive stance. Terrible odds for a witch, Ambrose says. But she is no witch, at least not a full witch. Sabrina deduces that "Ms. Wardwell" is actually Lilith, which means she killed her favorite teacher and has been posing as her to serve the Dark Lord. Lilith reiterates the Dark Lord's demands and warns that the Dark Lord will destroy everything and everyone in his path should she resist. Sabrina acquiesces despite her family's protests. She explains that she needs answers about her father and mother. Hilda warns Sabrina that she will be like a lamb led to the slaughter. Ambrose volunteers to go with her but Lilith says that Sabrina can only take her familiar Salem with her.
At Dorian Gray's Room, Father Blackwood bends the knee to the Dark Lord and pledges fealty. The Dark Lord orders him to rise and give a report about the Church of Night. Blackwood proudly informs the Dark Lord of his efforts to bring the coven back to the "old ways", renaming it Church of Judas. Seemingly unimpressed, The Dark Lord inquires about Sabrina. Blackwood tries to explain that Sabrina is dangerous, but surely Sabrina can't be too dangerous for the High Priest of Judas, the Dark Lord counters. Having had enough of Father Blackwood's nonsense, the Dark Lord silences him and scolds him for his poor job with the whole Church of Judas rebranding. As such, the church is now required to exalt and report to Sabrina in addition to himself. A dismayed Blackwood scoffs but is quickly challenged by a towering Dark Lord. Do you question your Dark Lord, he asks. Blackwood stiffens. Followingly, The Dark Lord orders that Sabrina's coronation and all attending festivities will be held at the Academy of Unseen Arts. Blackwood and his coven must accommodate them henceforth. He then dismisses Blackwood and Prudence.
Meanwhile, Roz frantically paces as she asks Harvey how they will stop the Gates of Hell from opening. Harvey tells her that his dad has a lot of dynamite for controlled explosions. Assuming they can find them, Theo adds. Roz reassures her friends that she has the Cunning and that she has been practicing. Harvey tells his friends to grab everything they need. The three set out with guns.
Back at the Academy, Lilith tells Sabrina that the Dark Lord won't be long and that he will want everything to be perfect. Sabrina recalls her role as Lilith in the Passion Play, she always wondered why Lilith bends to the Dark Lord and does his bidding. Lilith explains that she promised; serve him faithfully and she would become Queen of Hell. And you believed him, Sabrina questions. Lilith scoffs and merely tells her she wouldn't understand.
At first, the Dark Lord was kind and gentle. They would spend their days near the place he'd fallen and hit Earth, where thousands of years later would become the town of Greendale. Maybe that's why Greendale's so messed up, Sabrina remarks. Lilith explains that Greendale is a nexus and a cursed place. When Sabrina asks what happened next, Sabrina explains that the Dark Lord turned into a dark, horned creature after the fall of humanity. But Lilith continued to serve the Dark Lord because that is all she ever knew. Sabrina dismisses her for being weak.
Dorian arrives to inform them that the Dark Lord is ready and takes them to the Gray Room. At the far end of the mahogany table, the Dark Lord welcomes Sabrina and her familiar Salem. Not bothering with small talk, she asks what he wants from her. The Dark Lord demands respect and love but settles for gratitude. Sabrina asks why she should be grateful to him. The Dark Lord says that he gave her beauty, strength, and power above all other mortals. However, she did not ask for those things, but the Dark Lord thinks otherwise. The truth is that she's loved the power he has given her, reveled in it. He compliments Sabrina for her wrath and describes her as the fit consort He has been waiting for millennia. When Sabrina suggests Lilith, the Dark Lord responds that Lilith knows that her purpose is to serve. Sabrina's purpose, however, is to blow the Horn of Gabriel for him, opening the Gates of the Pit for the aristocracy of Hell to attend her coronation. She will wear the Crown, sit on the throne, and remake the world in Hell’s image once they have danced the Mephisto Waltz. He vows that all the demonic hordes will be freed and that the two of them will reign over Hell on Earth for all eternity. Well, that's certainly not an option for Sabrina, she has school to attend. The Dark Lord laughs and reminds her that she said no every step of the way and yet here they are. It's about time she accepted that the Path of Night is her only path and that every choice that she has made has led her here. He says that He has made quite sure of that and reveals that Nick Scratch has helped advance his plan.
Nick appears and tells Sabrina that the Dark Lord told him to befriend her but admits that he fell in love with her. Sabrina spits in his face. Nick says that he would never hurt her but that he did not know he was advancing the Dark Lord’s agenda. Sabrina is angry but the Dark Lord tells her not to blame him because it wasn't his choice; there is no such thing as choice, there is only his desire. Sabrina asks if her father conspired with him but the Dark Lord reveals that Edward Spellman is not her father, he is. Sabrina experiences a flashback to the vision of the twins and her father offering her to the Dark Lord. The Dark Lord tells Sabrina to submit and to blow Gabriel's Horn at sundown in the clearing where she signed her book. Sabrina flees and Nick tries to stop her. Salem hisses at Nick. The Dark Lord tells Nick to leave her be and that his work is done.
Meanwhile, Harvey, Theo, and Roz enter Tunnel 13. Roz touches Sabrina's mural and seizes a vision of the Gates. She says she can lead them to the Gates.
Father Blackwood gives an embellished account of his meeting with the Dark Lord and claims that the Dark Lord proclaimed his Church of Judas as the one true Church of Darkness. The coven hails Satan and tells the coven to take part in an Unholy Communion. The witches and warlocks step forward to drink the wine. Agatha and Dorcas reluctantly obey orders to step forward as Blackwood shouts Hail Satan.
Sabrina returns home with Salem and breaks the news to her family. Sabrina asks if her father Edward would offer up her mother Diana to the Dark Lord. Zelda says that Edward loved Diana and would never do that. Hilda says that might be true. Ambrose and Zelda react with shock but Hilda reminds Zelda that she was Diana's midwife. Hilda tells Sabrina that her mother struggled to produce a child so that she and Edward went to the Dark Lord who blessed them with a child. Hilda then recalls that Diana came to her and was worried about Sabrina because she thought that the baby wasn't Edward's. Zelda is shocked and asked why the Dark Lord would do such a thing. Ambrose explains that he has read apocryphal books on Satanic lore and that the Dark Lord perverts the Holy Trinity by siring a babe of witch, mortal, and infernal blood. He deduces this was part of the Dark Lord's plan to instigate the apocalypse. As the rain pours down, Sabrina realizes that the Dark Lord tricked her father and used her mother and that he now expects her to fall in line. Sabrina vows to defy Satan and says that she will always be a Spellman. She vows to fight the Dark Lord but admits she doesn't know how. Lilith returns and says she has an idea about how to fight the Dark Lord.
Meanwhile, Roz leads her friends to the Gates of Hell. Theo doesn't think that dynamite will work. Harvey asks Roz to do her cunning vision. Roz approaches the Gate and touches it with her hand. Roz is overwhelmed until Harvey shakes her out. Roz says she saw runes and symbols on the gate and thinks that these will keep them locked, likening it to a protection spell. Harvey realizes that they can draw paintings to keep the Hordes of Hell of bay. He asks Roz if she can help. Roz tells him she can help and transfers her powers to him. Harvey rapidly draws several symbols while Theo pastes them against the gate.
Back at the Spellman house, Zelda questions why they should trust Lilith. Lilith responds that Sabrina's defiance has given her hope that her story isn't finished, but they're not buying it. Lilith cuts out the act and states plainly that all she wants is the Throne and Crown, and if that means she has to gut the bastard then so be it. Sabrina says that Lilith is at least being honest. Hilda asks how they can defeat the Dark Lord since he is kind of a "god". Lilith points out that the Dark Lord has never been a god but is merely a fallen angel, a creature of the cosmos. While the Dark Lord is powerfully ageless, she reassures them that she has seen Satan bleed. She tells them that she knows his weak spots if they wish to listen. As Sabrina is currently powerless, the Spellman family will be the secret weapon. The Dark Lord will be expecting her in the woods alone, but Lilith reassures Sabrina that she won’t be alone and unarmed. She asks if anyone here knows how to smelt. They turn to Ambrose, who wields a blade of pure iron. Lilith says the blade won't kill the Dark Lord but will distract him and that they have to do exactly as she says.
In the woods, Lilith tells Sabrina to exploit the Dark Lord's greatest weakness: his arrogance, pride, and ego. She must flatter the Dark Lord and be in his thrall and should keep him facing her at all times. Lilith explains that the Dark Lord has two wounds on his back which have never fully healed, where his wings were ripped from His body. Lilith’s plan involves Sabrina trapping his foot with a horseshoe so that her aunts can stab him in the back with daggers forged in Megiddo, where Christianity was born. The Spellmans carry out Lilith's plan but the Dark Lord reveals that only the Spear of Longinus can kill him. He points the daggers at Zelda and Hilda's neck and throws Ambrose to the ground. The Dark Lord forces Sabrina to pick up Gabriel’s Horn in return for sparing the lives of her aunts. Sabrina grabs the horn from that altar and blows Gabriel’s Horn. The Devil says that the damnation game begins. He warns Sabrina not to defy him again and tells the Spellmans they are expected at her coronation. Ambrose asks now what. Sabrina says that we pray that Harvey, Theo and Roz are nowhere near the Gates right now.
Back in the tunnels, the three friends realize that the Gates of Hell are opening. Harvey proposes running but Theo thinks they don't have enough sigils. Theo tries to block the gap of the gates but is almost grabbed by the demonic horde. Harvey and Roz free him. Theo asks if the sigils will work and if Roz's cunning is right.
Back at the Spellman household, Lilith apologizes for the failure of their plot and says that she has been sent by the Dark Lord to prepare Sabrina for the ball. Lilith tells Sabrina she will make a wonderful queen. However, Sabrina says that the fight is not over and that she has been looking through the spell books on ways to fight the Dark Lord. She tells Lilith that she has been reading her father's journals. Sabrina says that Edward Spellman is more her father than the Dark Lord. Lilith leaves to prepare the demonic aristocracy. Sabrina tells Salem that she will find a way.
At the Academy, Father Blackwood is packing his bag. When Prudence inquires about this, he tells her to pack a suitcase for the twins and to bring only necessities. Prudence asks why they should run from the Dark Lord. Blackwood angrily responds that he will not bow down to a Spellman whore. Hence, they will be leaving Greendale by nightfall. What of the rest of the coven, Prudence asks. Blackwood reveals that he has poisoned them at Communion. Horrified by this, Prudence rushes to the Desecrated Church despite Blackwood's warning that leaving him now means leaving the twins forever. Taking a last look at her half-siblings, she vows to kill her father wherever he goes. She arrives at the Desecrated Church to find Agatha and Dorcas choking on poison.
Prudence teleports herself and the other Weird Sisters to the Spellman household. Prudence begs Zelda, Hilda, and Ambrose to help her sisters and reveals that Blackwood poisoned the entire Coven. She tells Zelda that they are still alive and are at the Desecrated Church. While Hilda and Prudence attend to the Weird Sisters, Zelda and Ambrose teleport themselves to the Desecrated Church. She tells Ambrose they will save as many of them as they can, starting with Melvin and Elspeth.
Meanwhile, Lilith finds Harvey, Roz, and Theo have succeeded in using the sigils to hold back the demonic hordes. Lilith is pleased with the mortals for keeping the Gates of Hell from opening.
Back at the Spellman household, Ambrose asks Prudence how her sisters are. Prudence thanks Hilda for saving their lives. Ambrose tells Prudence that Father Blackwood used them by exploiting their desire for a father. He says that Blackwood blinded them to the family that they already have. The two hold hands.
Sabrina reads one of her father's journals and finds the Acheron Configuration that held Batibat. She considers using it to trap the Dark Lord. Nick says he can help and appears in her room through astral projection. After asking for forgiveness, Sabrina reluctantly accepts his offer to help her prevent the Apocalypse from happening. Nick thinks that the Acheron Configuration can be used to trap the Dark Lord since it is based on the most sacred and complex bindings in nature, the human body. Her father was inspired by Leonardo da Vinci's sketch of the Vitruvian man but the Acheron is only as strong as the magic and binding spell behind it. Thus, this is not something Sabrina can do alone, especially without her powers.
Upon Lilith, Roz, Harvey and Theo's arrival, Sabrina's hope for the future is restored. She will require everybody's help. Nick's task is to fix the Acheron Configuration. She and her friends will proceed with a "glamour to end all glamours." Finally, Lilith's job is to trick the Dark Lord into thinking that everything is going according to plan.
At the Throne room, the Dark Lord and Lilith sit. Lilith claims that the aristocrats of Hell and Sabrina are awaiting her word. She has arranged a treat for Satan, a "bal masqué" of the flamboyant flavor he so loves. When signaled, the glamoured guests come down the stairs singing and dancing with their masks on. Afterwards, the Dark Lord crowns Sabrina, naming her Sabrina Morningstar, Proud Lady of Pandemonium, Maiden of Shadows, and Queen of Hell. The guests praise them. Then the pair dance the Mephisto's Waltz. During the dance, Sabrina flatters the Dark Lord to distract him from the guests' chants. Upon the Dark Lord's realization, they remove their masks, revealing themselves as the Spellmans and Sabrina's mortal friends. The Dark Lord is angered by her defiance yet again, but Sabrina replies she is a Spellman first. Ambrose throws the Acheron Configuration, trapping the Dark Lord inside. As they congratulate her for a job well done, the Dark Lord breaks his way out of the Acheron Configuration.
Lilith finally steps in and restrains the Dark Lord before he can harm Sabrina. They will need a stronger prison, and the answer to that is the human body, as it was created by the "False God". Nick volunteers in Sabrina's stead, reasoning he is the best binder and conjurer since Edward Spellman so he will be able to contain him. He confesses his love for Sabrina a final time, before trapping the Dark Lord in his body. The demon-possessed Nick tries to attack Sabrina but is knocked unconscious by Ambrose's sleeping spell.
As she leads them to the Gates of Hell, Lilith explains that Nick will have to remain in Hell with her, as it is the safest place. She alleviates any fears Sabrina holds for Nick's wellbeing, by vowing to take good care of Nick. As promised, Sabrina hands over her crown to Lilith, making her the new Queen of Hell. As the newly self-crown Queen of Hell, she bestows upon Sabrina two gifts. The first is restoring her witch powers and tells her not to give them up. When Theo asks about the second gift, she responds they will soon find out. Finally, Harvey hands the demon-possessed Nick to Lilith, who then carries him through the Gates of Hell. Sabrina rubs her head against the Gates of Hell and weeps for Nick.
Back at the Academy, Ambrose and Prudence embark on a quest to hunt down Father Blackwood. Before leaving, Prudence beheads Blackwood’s statue. She tells Ambrose that her father won’t be easy to hunt down and to kill. Ambrose vows to seek his true destiny as a witch, something shared by Prudence.
Later, Zelda and Hilda watch the handful of witches and warlocks that have survived Blackwood's mass poisoning in pity. This is what's left of the Coven. Hilda asks what they should do since they don’t have a Dark Lord to worship anymore. Zelda says that they are now the Church of Lilith and that as High Priestess she will figure it out.
At Cerberus Books, Sabrina meets up with her mortal friends. Sabrina tells them that all her life she believed that she was half-witch, half-mortal but that she has realized that she is something else. Theo asks her what she is going to do. Sabrina says that she doesn't know but will figure it out including finding out about her mother's side of the family. Sabrina thanks her friends for saving the world and says they can work together against the forces of Satan. Theo thinks they are like a club now. Harvey proposes the name Fright Club. Shortly later, the real Ms. Wardwell enters the shop and tells them that she woke up from the most vivid and incredible dream. She recalls seeing the Night of the Living Dead but that she is famished. Sabrina realizes that this is her second present from Lilith. Sabrina tells her mortal friends of her mission. Salem meows, prompting Sabrina to call her group five. She tells them that her mission is to go to Hell and get her boyfriend back.
- The Mephisto Waltzes are four waltzes composed by Franz Liszt from 1859 to 1885.
- Mephisto or Mephistopheles is one of the chief demons of German literary tradition.
- Luke Cook, who plays Lucifer Morningstar, also played Dorian Gray in The Librarians.
- During their final confrontation with Lucifer, Sabrina, along with her friends and family, perform the song Masquerade from the musical Phantom of the Opera.