The gunshot fired by Mary Wardwell echoes throughout Spellman Mortuary. Sabrina and Ambrose find Zelda bleeding out on the floor. Ambrose runs for help as Sabrina stays by Zelda’s side. He returns with Prudence and Mambo Marie. They take Zelda downstairs into the embalming room and remove the bullet. They’re going to need great strength if they are going to save her. While Zelda remains alive, she is stuck in limbo, Mambo Marie explains. All they can do is burn the violet candles and wait to see if Zelda can find her way back. They are startled by sudden loud wailing.
Sabrina, Ambrose, and Prudence find a banshee, otherwise known as the wailing woman, lurking outside the mortuary. It’s an omen, meaning at least one member of the Spellman family is going to die soon.
Lucifer awakens in his body, free of the flesh Acheron. He confronts Lilith, who he plans to kill for the part she played in usurping him. However, Lilith reveals that she gave Blackwood the Mark of Cain before he left, which means no one can hurt him. And in exchange, he gave Lilith the Dark Lord’s seed. She is pregnant with his child. A male heir to his throne. He tells Lilith that she has not been pardoned, rather a stay of execution. He then orders her to summon the Infernal Court and tell them that "Daddy’s back, and he’s very, very angry."
Pan and Nagaina discuss how Sabrina infiltrated the carnival and killed four of their tribe. The great flowering of the Green Man is almost upon them. Nagaina calms him down and tells him that the blood of their lost tribe members nourishes the Green Man. Faustus Blackwood is dragged into the tent after he was found hiding in the shadows. He reveals that he cannot be killed as he bears the Mark of Cain. He’s come seeking an alliance. He wishes to see the Church of Night dead, same as them. They can kill the witches in their beds as they sleep. There are secret tunnels and a secret door that he can lead them in through. Pan agrees to lend Faustus some of his men to raid the Academy of Unseen Arts. They stole something from Faustus, and he wants to use the pagans to get it back.
At the Putnam house, Theo and Robin sit at the edge of the bed. Theo is admittedly nervous. He never thought he’d meet anyone who would accept him as he is. Not until he met Robin, who removes his hat and shirt to reveal his pointed ears. Robin is a hobgoblin. He possesses the ability of super speed. He then takes a seat next to Theo at the edge of the bed and asks if he’s ready to take the next step in their relationship. Theo and Robin proceed to have sex as only virgins can be sacrificed to the Green Man.
As Harvey and Roz make out on his bed, Roz has visions of Sabrina and Harvey together. She asks if he still has feelings for Sabrina, and he says that he doesn’t, though she keeps seeing glimpses of them together. Harvey assures Roz that he’s all in with her. He doesn't care that the spell Caliban gave him didn’t work. Roz then asks what spell Harvey is referring to.
Lucifer returns to Hell take control of the throne. He orders his disciples to kneel before him. When Purson, of the Plague Kings, questions his authority, Lucifer snaps his neck. Caliban confronts Lucifer, introducing himself as Prince of Hell, though Lucifer doesn’t acknowledge his claim. Beelzebub interjects to inform Lucifer that they're in the middle of the quest for the three objects of the Unholy Regalia. Infernal protocol must be followed and the contest must be seen to the end. Caliban and Sabrina each have found one item. Whoever finds the third, Judas Iscariot's 30 pieces of silver, will sit upon the throne of Hell, and not even Lucifer can interfere with that.
Sabrina, Prudence, and Ambrose recount the current obstacles they are up against, including the encroaching pagans, Zelda trapped in limbo, and Hilda buried in the Cain Pit. Ambrose thinks that he knows of a way to gain power, though it won’t be easy. Ambrose found a siphoning spell. If they can get the hedge witches into the center of the stone circle, they can take their energy and replenish their coven. Unfortunately, with the hedge witches being older and few in numbers, the siphoning would likely kill them. Sabrina suggests that they find another way. Unless Sabrina knows of a more nubile coven to bring into the circle, they don’t have any other options. Sabrina claims that while it may be the very definition of an unholy Magdalene, she believes that she already belongs to another "coven." The Baxter High Ravenettes.
Mambo Marie prays to Baron-yo, leaders of the Gede for mercy as it is not yet Zelda’s time.
While trapped in limbo, Zelda finds herself back in the Spellman house, where Hilda is whipping up breakfast. Hilda waits for Dr. Cerberus to join them, but Zelda reminds Hilda how she transformed into a giant spider and killed him. And then, Zelda killed her. Hilda’s buried in the Cain Pit. And then Wardwell shot Zelda, who deduces that they’re in the Nether Realm. They have to find a way back to stop the pagans. However, they are speechless at the arrival of their brother Edward.
At Baxter High, Sabrina tells Roz that she’s in need of a young, energetic group of women who often chant and move in unison; the Ravenettes. She needs Roz’ help with a special performance at the Academy. Ambrose has a plan to re-energize the Church of Night members, and she’ll need the Ravenettes. Sabrina then asks Roz what it was that she wanted to talk about, but Roz tells her it can wait. As for how Sabrina plans to get them to the Academy, she’ll use a spell of persuasion. Lizzie arrives and asks what they’re talking about.
Sabrina and Roz take Lizzie and the Ravenettes to the Academy, where Ambrose and Melvin wait to perform the ritual. Prudence arrives in search of Dorcas, but no one has seen her. Sabrina, Ambrose, Prudence, and Melvin begin chanting in Latin as Roz, Lizzie, and the Ravenettes perform their flash mob routine. The ritual goes as planned, leaving the Ravenettes weakened and tired. Faustus arrives through the secret door with the pagans. Sabrina closes the door, and the Church of Night and Ravenettes take each other’s hands and teleport to safety. Roz, Lizzie, and the Ravenettes are teleported to Baxter High, where everyone save for Roz has forgotten their stint at the Academy.
Sabrina, Ambrose, Prudence, Melvin, and the remaining members of the Church of Night teleport to Pandemonium. Sabrina returns to the Academy to retrieve the effigies that are filled with the energies that Hilda and Zelda need to return to the land of the living. There, she is confronted by Faustus, who inquires about the hedge witches in the Desecrated Church, whom he left unharmed, as they’re not worth killing. He advances towards Sabrina, but she teleports away. The pagans return with Circe and Dorcas, the latter murdered before they arrived. Agatha arrives covered in Dorcas’ blood and admits to having taken her own Sister’s life. Blackwood takes Agatha in and tells her that he wants every last Spellman dead. He's also still in search of the egg that Ambrose and Prudence stole.
Sabrina returns to Hell to tell Ambrose, Prudence, and Melvin that her father is no longer bonded to Blackwood. Lucifer and Lilith arrive and inform Sabrina that the Plague Kings have called for the third and final challenge. It’s up to Sabrina to retrieve Judas Iscariot’s 30 pieces of silver and secure the throne of Hell for the House of Morningstar. However, Sabrina would rather attend to her aunts. Ambrose and Prudence tell Sabrina that they'll deliver the effigies to Hilda and Zelda and protect them from Blackwood until they recover. The power siphoning might have worked, but Ambrose fears it is only temporary, and with a war brewing with the pagans, they’ll need power, which Sabrina could gain in winning the Unholy Regalia. Lilith reveals that she’s pregnant and that Sabrina has a little brother on the way. Sabrina tells Ambrose and Prudence to protect her aunts while the rest of the coven stay hidden in Hell.
Zelda and Hilda ask if Edward knew the truth about Sabrina's lineage; the Dark Lord is her father. Edward admits that he did. He and Diana made an appeal to the Dark Lord, begged for a child. He didn’t tell Zelda and Hilda because Sabrina needed to find her own path, as Zelda must find hers now. Edward will guide her as he always has. Zelda recalls Mambo Marie saying that everyone has a mèt-tèt. A spirit that’s been with them all their lives and guides them. Zelda concludes that’s why she’s in limbo; to find a solution to all their problems.
Edward takes Zelda and Hilda into the past, when they were students at the Academy. Time exists simultaneously in the Nether Realm. They’re simply visiting a memory of Zelda and Faustus studying in the library. Zelda questions what Faustus is reading that has him so upset. He says nothing and tears a piece of paper from a book and throws it in the trash. Zelda and Hilda retrieve the page, but can only make out the moon symbol inscribed on the page.
As Caliban receives counsel from the two remaining Plague Kings, Beelzebub and Asmodeus, Lucifer and Lilith prep Sabrina for the final challenge. Lucifer tells Sabrina that only Judas himself knows where the silver is. And Lucifer is the one person who can take Sabrina to Judas. Lilith warns the Dark Lord against interfering. Should the kings find out, the challenge could be deemed a forfeit. As the challenge commences, Lucifer telepathically tells Sabrina where to find Judas. In a volcanic cave, embedded in the walls with Cassius and Brutus. Together, they make up the three worst betrayers in history.
Ambrose and Prudence return to the mortuary, where they inform Mambo Marie that the effigy is infused with life force. With any luck, its power will transfer into Zelda. Mambo Marie informs them that it is no longer a matter of Zelda’s physical body needing healing. It’s her soul that must find its way back. With the Academy under the control of Father Blackwood and the pagans, Ambrose fears that they’ll be coming to the house next. He asks Mambo Marie to watch over Zelda as they protect the house. He then orders Prudence to stay inside and protect the inside while he holds the perimeter against the banshee and Blackwood.
Sabrina finds Judas right where her father said she would; embedded in a stone wall inside a volcanic cave. Judas reveals it was Lucifer who put him there. Sabrina asks where to find the 30 pieces of silver he was paid to betray the Nazarene. In return for his compliance, she offers him water. He tells Sabrina there is any easy way, in which the silver simply appears to her and a harder way, in which she must seek it out. Sabrina chooses the easy way. She must betray someone with a single kiss, as Judas did. Sabrina reluctantly agrees.
Sabrina portals to Harvey at Baxter High. He asks if Roz talked to her, causing Sabrina to wonder if something happened between the two of them. Harvey’s no longer sure where they stand. As Sabrina goes to kiss him, Harvey professes his love for Roz, and Sabrina backs out. She tells Harvey that he and Roz are great together and they shouldn’t let anyone ruin that. She then portals back to Judas to inquire about the hard way. He tells her about the Field of Blood. A burial ground where his silver is buried in a crypt with the first vampire, Vlad the Impaler. The silver is in a bag at his side. She must count them to ensure they’re all there. Sabrina now has to portal to his tomb, but she first gives Judas the water he was promised.
Ms. Wardwell enters the classroom and orders the students to settle down. Mrs. Meeks then announces over the intercom that Baxter High has been invited to the Final Night Festivities at the town carnival. Free admission and rides. Roz, Harvey, and Theo are then called into the Principal’s office. There, they are confronted by Pan and Nagaina. Harvey, Roz, and Theo hide in the library. Pan and Nagaina transform into their true forms and tell Harvey, Roz, and Theo about the return of the Green Man. However, one last thing is needed for him to rise; the innocent blood of a young virgin. Just as Nagaina is about to find Harvey, Robin arrives at super speed and whisks him, Roz, and Theo to safety. Mrs. Curtis enters the library, turns the lights back on, and asks if she can help Pan and Nagaina, who claim they were just leaving.
Harvey, Roz, Theo, and Robin reconvene in an empty classroom, where Theo explains that Robin saved them, and he is a hobgoblin. They have to leave Greendale and convince as many people as they can to leave with them. The Green Man is coming back and all who are flesh will die. Harvey, Roz, and Theo refuse to leave. They need Sabrina if they stand a chance to defeat the pagans, but she’s in Hell. Roz believes that they can use the magick marker she uses to message Nick to make contact with Sabrina.
Edward guides Hilda and Zelda back to the Mortuary. Back to the day of the plane crash that killed him and Diana. A younger Zelda and Hilda find Sabrina crying on the floor. They pick her up while concerned for the well-being of Edward and Diana. As they leave, Edward shows Hilda and Zelda the blanket in Sabrina’s basket, which has a half-moon stitched on it.
At Dorian's Gray Room, Sabrina tells Nick that both her aunts were shot and that Blackwood has come back and is working with the pagans. And now, she has to find the final piece of the Unholy Regalia before Caliban does. Nick remarks that the Sabrina Spellman he knew would never abandon her family for a quest. He then wishes Sabrina luck before she portals through one of Dorian’s photos. Nick then receives an S.O.S message on his hand from Sabrina’s magick marker.
Just as Judas said she would, Sabrina finds the silver in Vlad the Impaler’s crypt. Vlad is nothing more than a skeleton. Sabrina takes the silver and counts it to ensure all 30 pieces are accounted for. Vlad rises from his crypt, full of blood and flesh once more. He compels Sabrina into compliance. He asks if his father sent Sabrina, she replies no, explaining that she was sent by Judas, unaware that Judas is in fact Vlad’s father; the father of vampires. He compels Sabrina into allowing him to feed on her. When he does, her infernal blood burns him. Sabrina then breaks free of his compulsion and kicks him in the face.
Nick teleports into Harvey’s garage to find Harvey, Roz, Theo, and Robin awaiting Sabrina. He explains that the magick marker is attached to him and that only he receives its messages. They tell Nick that the great flowering is upon them. The pagans have been trying to resurrect the Green Man for centuries, and the time has finally come. "All flesh fails when he flowers", Robin says. He explains that first the locals are "seeded." They're implanted with a spore, something they eat that can grow inside them. Theo believes that’ll be through the caramel apples they're going to give away. And then, when the Green Man is ready, when he's ripe with the blood of a local virgin, that is when he will bloom. And then comes the pollination. It'll be the end of everyone in Greendale. Pan, Nagaina, Circe, and the pagans barge into the garage and capture them. Nagaina reminds Harvey of what she told him when they first met, that once she has a virgin’s scent, they can’t hide from her.
Ambrose and Salem continue to defend the perimeter. He tells Salem to claw the banshee to pieces if she tries to get anywhere near the house.
Inside the Spellman house, Prudence is on guard. She follows the sound of Agatha’s laughter. She finds Agatha with a knife in hand, covered in Dorcas’ blood. Agatha charges at Prudence with a knife, and Prudence is forced to kill her, stabbing Agatha in the abdomen with her sword. Agatha tries to warn Prudence that Blackwood is near, but she fails to get the message out, allowing Faustus to sneak up from behind and stab Prudence.
Ambrose rushes back inside to find Prudence bleeding and dying from her wounds. Ambrose holds her tight, as she reveals that Blackwood is inside, and he’s looking for Judas and Judith, among other things. Prudence tells Ambrose to stop him. And so, Ambrose lays Prudence back on the floor and teleports away. Prudence, in her dying moments, places her hand over Agatha’s.
After exploring their past, Edward takes Hilda and Zelda to see their future. They enter a room, where a group of witches are standing vigil, praying for a safe crossing to the afterlife for a much older and dying Zelda. Sabrina tells Zelda that she loves her and couldn’t have asked for a better mother, before telling her to rest and let go. Edward then gestures towards the framed photos on the wall of the new moon, half-moon, and full-moon. Maiden, Mother, Crone. She realizes what Edward has been attempting to show her. It’s the three phases of the moon and the three phases of a witch’s life.
Zelda returns to her body and awakens with the answers to the coven regaining power and defeating the pagans. However, she’s too late. Before her stands a banshee. She looks over to her left to see Faustus standing over Mambo Marie’s body. He then stabs Zelda in the chest, killing her.
Sabrina returns to Judas. He asks to feel the weight of the silver coins in his hand one last time. Sabrina gives him the coins, and Caliban reveals himself after having posed as Judas. He then does a spell that frees him and embeds Sabrina into the stone wall. He asks why Sabrina didn’t take the easy way and betray someone with a kiss. Sabrina replies that she’s not a betrayer. However, Caliban begs to differ considering Sabrina chose the quest over her family. While Sabrina was dashing off, collecting trinkets, Caliban was arranging a coup. Caliban then reveals to Sabrina that Lucifer and Lilith have been embedded into the stone walls as well. He encases Sabrina in stone completely and leaves as he has a mortal world to conquer and a tenth circle to create.
Nick, Harvey, Roz, Theo, and Robin are taken to the carnival by the pagans, who kill Nick and Robin, and entrap Harvey inside the Green Man as his virgin sacrifice. Pan, Nagaina, and Circe remove the hoods from Roz and Theo so they can watch. Theo and Roz scream helplessly with their hands bound and mouths gagged. Harvey pleads out for help, but his prayers go unanswered. Harvey is killed as the vines of the Green Man stab into his chest. And with that, the pollination begins. Roz and Theo scream for Sabrina to come and save them, unaware that she is encased in stone.