While Gunmar searches for the Staff of Avalon, Jim and Toby head into the Shadow Realm to rescue Claire's spirit and return it to her body.
They have Claire tied up. She tries to get them to release her, but they refuse. Blinky then comes in and reinforces her bindings. He tells them AAARRRGGHH!!! didn't return as scheduled. Blinky knows Claire is possessed and Jim mentions the name Morgana, scaring him. Morgana as Claire starts explaining who she is. Blinky says it's worse than he could have imagined. She was Merlin's apprentice, but she spits on his grave now. Merlin sacrificed himself to banish her. She tells them that Gunmar knows how to bring Eternal Night and all they can do is watch it happen. Blinky asks her how. Jim stops him and asks him if he can save Claire. He admits that he can't, but Jim thinks he knows someone who can.
Strickler finds chaos in the room as Claire floats around. He pulls out a skull and then the Book of Ga-Huel. He consults it and says there's always a cost for dabbling in dark magiks, but they don't have a choice. He shows them what Morgana is doing with Claire. Toby realizes that Claire isn't casting a shadow, helping Strickler realize it's the Skathe-Hrün, the Shadow Staff which is a relic of Morgana. She's the mistress of shadows, which is why she doesn't cast a shadow. She is one. Claire's spirit is trapped in the Shadow Realm. Someone had to find her spirit in the Shadow Realm and return it to her body. They must do it quickly because the longer Morgana stays in her, the stronger the hold on her. Jim and Toby agree to go find her while Strickler stays behind to hold the portal open with the staff. Blinky will stay with him to keep an eye on them both.
Draal drags AAARRRGGHH!!! to follow Gunmar. Gunmar says it'll become clear why he has to come when they get there.
Jim and Toby return with everything Strickler told them to retrieve, including Claire's stuffed bunny from when she was a baby. He gives them an incantation to say and then opens the portal for them. Jim and Toby step inside.
Toby and Jim fall around the Shadow Realm. Jim finally stops them and they start to swim around. They hold the bunny and say the incantation. It's head spins around and it starts to shake. Then it pulls them along behind it. They finally stop near a house that looks like Claire's. Inside, Toby turns on the TV to see clips of Claire's past adventures. They follow the sound of a baby crying upstairs as Jim calls out to her. They enter a room and find Enrique's crib empty. Suddenly, Claire's spirit comes in to comfort Enrique. She's not aware of Jim and Toby and walks right through them.
Strickler is struggling to keep the portal open. Blinky's doubting Strickler's decision to have them go. Morgana tries to play into Blinky's insecurities, but he just leaves the room. Morgana then taunts Strickler, appearing to him as Barbara, offering him the heart of another. Strickler doesn't believe it's possible, but Morgana says it is. All he has to do is drop the staff and seal their fate. Blinky comes in and tells him not to, but she throws him out of the room.
Claire's spirit continues to work with no awareness of Jim and Toby. Jim and Toby try to figure out how to get Claire out with them. Jim is able to knock her stack of books off the desk, but she simply bends down to pick them up, so Jim kicks one across the room. Then he uses a marker and paper to write Claire a note. She reads the note and then starts to hear Toby calling to her. She asks them what they're doing there. She thinks she's dead. They explain that she isn't, but they have to get her back. They lead Claire out of the house and use her stuffed Bunny to help them get back to the entrance. Jim tries to say the incantation backward, but they've forgotten how it goes, so they'll do it the hard way. Claire leads them toward the portal.
Morgana continues to try to get Strickler to let go. He says a stolen heart is never truly yours. He starts to give in as Blinky comes in. Morgana uses an incantation to fling the staff into the portal and close it.
Jim, Claire, and Toby see the portal close and then see the staff flying by. They have to get it because it's their own way back. They all try to catch it. Jim finally grabs it, but gets dragged around by it before flying off. They know Morgana is controlling it. Strickler realizes she's getting stronger. Strickler pulls out a blade to stop her, but Blinky stops him.
They continue to chase the staff, but can't catch it. Claire finally uses an incantation, which draws the staff to her, but Morgana pulls it away again.
Blinky blocks Strickler from attacking Morgana.
Claire tries again and fights against Morgana's control. She is able to retake control and uses the staff to get them out.
Claire's spirit is back in her body. They free her. Claire says Morgana is gone, but she remembers things from Morgana's head. She's able to bring the staff to her. Claire doesn't think it'll be the last they see of her.
Gunmar leads them into the Temple of the Pale One and then the Temple of the Dark One. Morgana's magic is strong there, which weakens the walls of her prison. Gunmar gives Morgana the eye of Angor Rot, who wants to use AAARRRGGHH!!! as bait. She resurrects Angor Rot, giving him his soul and a bit of her own to serve her. They all bow to her. Angor Rot says this time, he'll destroy them all.
- Kelsey Grammer as Blinky
- Emile Hirsch as Jim Lake Jr.
- Charlie Saxton as Toby Domzalski
- Lexi Medrano as Claire Nuñez
- Jonathan Hyde as Mr. Strickler
- Fred Tatasciore as AAARRRGGHH!!!
- Ike Amadi as Angor Rot
- Clancy Brown as Gunmar
- Lena Headey as Morgana
- Amy Landecker as Barbara Lake
- Frank Welker as Goblins
- Angor Rot is officially resurrected by Morgana.
- Claire is freed from Morgana's control, but the witch is close to being revived.
- The title is a reference to the 2005 horror film The Exorcism of Emily Rose.
- Additionally, in the first scene where Strickler arrives at Claire's house, it is dead night and with lights illuminating from Claire's window. This is a scene replication of the horror film The Exorcist.
- Archived scenes from Parts One and Two are shown when Toby turns on the television at the Nuñez house within the Shadow Realm.
- Along with the usual grunts and yells, Anton Yelchin provides the dialogue for Jim in these archived scenes.
- This is the episode that reveals that Morgana created the Changelings all those years ago.