Many years ago, Rupert Giles and his punkband, Wretched, were performing in an underground club, when his grandmother, Edna Giles, came to find him. Later, backstage, Edna came to see him. She told him she worried about him, because she had heard disturbing things. She gave him an uplifting speech about standing up against he darkness of magic and demons, but then Rupert showed her his Mark of Eyghon.
In the present, Nadira and the other slayers were not doing well in their fight against Eyghon and his zombie horde. More slayers were being knocked unconscious and possessed by Eyghon. Luckily, Angel and Faith entered the fray, helping the girls fight the slayers. Giles (under the control of Eyghon) approached Faith and distracted her, which allowed him to knock her out. Nadira reacted quickly and gave Faith a shallow cut, this allowed her to wake up before Eyghon could gain control of her. Angel meanwhile fought off Giles and then went up against Eyghon himself. This allowed Faith, Nadira, and the other girls to escape. Nadira was angry that Faith worried about Angel, but Faith gave her a harsh but fair talking to, about how she had endangered the girls. Angel managed to give Eyghon quite a few injuries before escaping through a window and jumping into Nadira's car just before it left. Eyghon was furious, but with at least three slayers under his control, confident that he could exact his revenge.
Angel, Faith, and the slayers headed for Alasdair Coames for help. He revealed that Eyghon could only be killed by decapitating his true body, any other apparent death, would allow him to take control of any nearby corpse or unconscious person and survive through it. Angel revealed that as Twilight, he had already received news that Eyghon was still alive. When his powers were fully restored Eyghon wanted revenge on Ethan and Giles, but they had both already died. Alasdair explained that because Ethan and Giles wore the Mark of Eyghon he could control their corpses regulary. Angel then revealed he knew Eyghon owned Giles' soul and that therefore, he knew he could try to resurrect Angel; as Eyghon owned Giles soul, it could not have left the Earth dimension.
They worried that Eyghon might go into hiding, but Faith reveals that in the brief moment she was nearly possessed she saw Eyghon's plan. Eyghon wanted to re-create his zombie kingdom on Earth, but without magic, the bodies of those he possesed burnt out too soon. Only Giles and Ethan remained. So Eyghon made a deal with Whistler, Pearl and Nash, and they provided him with magic items (such as those stolen from the Giles residence). With it, Eyghon could spread his zombie-plague across the world, thus effectuating an evolution of humankind such as Whistler spoke about. Nadira wondered why Eyghon wanted the girls, and Angel explained that Eyghon probably did not trust Pearl and Nash and that the slayers would be his elite soldiers.
They formulated a plan where the slayers with edged weapons attack the zombies and those with blunt weapons attack the possessed Slayers. Angel would attack Eyghon, because he was immune to possession. Angel revealed that because Eyghon was too strong for him alone, he called in the help of someone else who was immune to possession, another vampire with a soul: Spike!
Eyghon was previously believed to have been destroyed in "The Dark Age", but when the vampire in Angel forced Eyghon out, it took control of a dead rat laying about and survived through it, and later transferred its essence to a knocked-out homeless man.
Angel called up Spike to help him against Eyghon the Sleepwalker. The phone conversation was explictly seen in "A Dark Place, Part Five".
Faith commented that fans of the zombie genre generally do not like the modern take on zombies, which includes them running, and that the fact that this zombie could talk would "break the internet", referring to heated emotions expressed on the internet over such fan topics.
Giles - "I am cut to the quick. Turn away, I can't bear for you to see me weep."
Edna - "No one who walks in our world does so unscathed. We all have our demons, Rupert. Often quite literally. One does not give up. One fights. One perseveres and overcomes them. We cannot escape the dark, Rupert. But we can refuse to let it own us."
Faith - " (shoots a zombie with a crossbow) Hey. Chatty Cathy. Hardcore fans don't like zombies who run. You keep talking, you're gonna break the internet."
Nadira - "You're worried about him? I'm worried about leaving our friends. "
Faith - "Jesus, Nadira, get your head out of your ass for once."
Angel - "Eyghon's not stupid. He doesn't trust Pearl and Nash. Whistler, maybe. He's all about balance. And making part of the planet hell might be part of his plan to make the other half paradise. But he knows Pearl and Nash don't like sharing power. They won't trust him anymore than he trusts them. Greed recognizes greed. He's afraid they'll try to double-cross. He wants an army of superhuman warriors whose bodies are infused with magic. So they'll last. He's already got enough to do a lot of damage. But he needs more. We need to take him out before their numbers grow."
Spike - "Right. No more weeping and moaning, ladies. And yes, Angel, I saw you there. Spike's come to save the day. As bloody usual."