Ruby's child emerges from his incubation chamber fully grown doppelganger of Ash. Ruby tells him that he needs to be a spitting image of Ash in order for her plan to succeed and has him cut off his own hand.
At the house, Brandy comes down stairs dressed for the school dance, intending to find out for herself if Ruby is in fact what Ash says she is. Ash is at first apprehensive, but Kaya (disguised as Kelly) convinces Ash to let her go. Ash agrees but decides to go with her in case something goes awry.
Kelly's soul contacts Pablo via the rift in the basement of the hardware store and tells him how she was killed by Ruby. The rift closes as Kelyl is chased away by an unseen presence. Pablo heads out to find Ash.
Ash drops Brandy off at the school and sends Kelly along with her and he will go around back. Brandy and Kelly meet with Ruby privately. With the help of Kaya impersonating as Kelly, Ruby is able to persuade Brandy into believing that Ash is really the demon.
Two teens leave the dance to smoke pot when they come across Ash, who subsequently kills them when he's revealed to be the doppelganger. Ash eventually locates and confronts his evil double and a fight ensues, but Demon Ash gets away when a cop shows up and apprehends Ash, thinking that he is the one who has been on the killing spree.
Kaya incapacitates the cop in order for Ash to escape and hunt down his double.
Pablo arrives and encounters Kelly, and while he is first surprised to see her alive, he is able to trick her into revealing herself as Kaya. She attempts to kill Pablo but he escapes
Demon Ash crashes the school dance and begins slaughtering countless party goers. Brandy, having witnessed her father committing such an act, believes Ruby was right all along.
When the real Ash catches up and walks into the dance, Demon Ash leaves. Ruby intentionally gets herself impaled on Ash's chainsaw to make Brandy think that her father killed her. With her supposed dying words, Ruby tells Brandy to use the dagger to kill Ash.
Brandy attempts to use the dagger on Ash, but is unable to bring herself to do it.
Pablo runs into Demon Ash, who attempts to kill him as well and chases him back into the gym. Brandy comes to realize that there were really two of them, and realizes that Ash was telling the truth.
Ash is able to kill his double by blowing his head off.
Ruby, furious that her plan failed, recovers from her injuries and throws the dagger into Brandy's back. Ash is overcome with emotion as Brandy dies in his arms.
Brandy awakens in the underworld and is chased away screaming by an unseen creature.