At the airport, Buffy, Dawn, and Xander wait for Willow to get off her plane and talk about how uncomfortable they feel about the situation. The plane clears, but the three don't see Willow. The scene repeats as Willow gets off the plane, but she doesn't see her friends waiting for her. A young man spray paints a wall of a construction site as a demon taunts him from the shadows and then attacks the frightened man.
Willow lets herself into the Summers house, which appears to be vacant of her friends. Going up to what used to be her room, but now has been claimed by Buffy, Willow remembers the last time she was in the room. A door closes and Willow goes to investigate, but still her friends are nowhere to be seen. Alone, Willow curls up on the couch. Buffy, Xander, and Dawn return home and after talking about how Willow did leave England, but she had opportunities to divert to another location other than Sunnydale. They hear a noise upstairs and check it out, but find nothing. In the living room, the three talk about the reason for Willow's disappearance.
The next morning, Willow walks over to the magic shop and finds Anya cleaning up the magic shop. Anya is very cold to her and Willow feels guilty about everything. They talk a bit and Anya fills Willow in on everyone's activities since she's been gone. Willow checks out Xander's construction site and instead of Xander, she finds a skinned body. At the same time, Xander and Buffy are looking at the body and the familiar sight makes them wonder if Willow is back after all. Unbeknownst to them, a disgusted Willow climbs a ladder to exit the site.
Willow walks the halls of Sunnydale High and proceeds down to the basement where she finds Spike acting insane. He talks to Willow about the dead body, but also carries on a conversation with something else in the room Willow can't see. Buffy and Xander maneuver through the basement and find Spike seemingly talking to himself. Buffy and Xander try to get information from him, but Spike is simultaneously conversing with Willow, so his words make little sense. Spike suspects they can't see each other and that Willow's responsible for it. Buffy and Xander interpret some of Spike's comments to mean that he knows about Willow and they suspect she might have something to do with Spike's unstable condition.
Willow goes to Anya at her apartment for help in finding the demon that skinned the guy at the construction site. Anya helps Willow cast a spell to locate demons all over Sunnydale. After the spell is complete, Willow asks Anya to teleport to one particular location to a cave just outside of the town. But Anya reveals that she can't for non-vengeance business as a result of her recently undoing a spell. Instead, Willow takes the long way and walks there herself. At the Summers house, Dawn immediately begins searching on the computer for demons that skin people. Although Buffy thinks it's a waste of time, Dawn soon finds a demon that meets their specifications named Gnarl. The demon paralyzes its victims with its nails, and then eats strips of skin from the body and drinks the blood.
Realizing they need to search for a trail of blood, Buffy decides to recruit Spike to smell the way. He leads them to a cave where the demon can be found. Willow is already there investigating the cave and the Gnarl spots her. The rest of the gang enters the cave as well, but they don't see Willow. The demon scratches Dawn's stomach and paralyzes her. Buffy and Xander take Dawn out of the cave and cover up the entrance, unintentionally leaving Willow with Gnarl. Trapped in the cave, Willow listens to the demon taunt her from the shadows. He slices her abdomen with a nail and thus paralyzed Willow is helpless against him as he sucks at the wound and starts to slice away slivers of her skin to eat.
Buffy and Xander carry a completely paralyzed Dawn into the living room while Buffy researches the Gnarl and the way to save Dawn. Anya is called to stay with Dawn while they prepare to return to the cave to kill the demon and save Dawn. Anya talks about seeing Willow and reveals that Willow may be at the cave, whilst she moves a paralysed Dawn into funny poses. Panicked that Willow is trapped in the cave, Buffy grabs Anya to join them at the cave. Once Anya reveals that she knows about Gnarl, Buffy insists she come along. Gnarl continues to eat Willow's skin as he tells her that her friends have abandoned her and she's all alone for him to eat. Buffy arrives and attacks Gnarl while Anya tends to a badly injured Willow who still can't see her friends. While Buffy fights Gnarl, Anya informs Willow that her friends didn't leave her alone.
Buffy pokes the demon in the eyes with her thumbs, successfully killing it and ending the paralysis on both Willow and Dawn. Buffy and Xander look where they think Willow is while Anya runs for help, and slowly the spell making them invisible to each other wears off. Willow is relieved to see her friends and glad they didn't abandon her.
In the morning, Willow meditates and uses magic from the earth to re-grow the skin she lost. Buffy stops by and talks with Willow. Willow reveals that her fear of seeing her friends and their judgment of her led to the invisibility problem from which they all were suffering. Buffy confesses that she briefly suspected Willow of the grotesque killing, but Willow doesn't blame her for that. Willow struggles to start meditating again, but she's still weak. Buffy offers her Slayer strength to her friend and joins in the meditation.