Zankou has the Book of Shadows - and now he's after the Nexus. If he gains control of that, it's game over for the forces of good. But wait, there's more! Inspector Sheridan has contacted Homeland Security about Brody. The agents reveal they know all about the Sisters, and they're ready to take them down.
Zankou brings in a legion of demons to manually dig for the nexus. They can't use magic, because the nexus would interpret that as a threat. When they dig down to where the nexus is, Zankou recites the spell to take the nexus in. But even from Magic School, the sisters can strike back. Their spell ejects the nexus from Zankou. A furious Zankou resolves to check the book for ways to counteract the Charmed Ones. The sisters try to get the book by calling in reinforcements. All the good magical creatures they've helped in the past - leprechauns, fairies, trolls, valkyries, the whole lot - attack the demons so the sisters can take a shot at the book. They even cast a spell on Zankou that turns him (mostly) into a pig. But the Book doesn't recognize the sisters anymore, and they're repelled by a protection spell. They need to regain their confidence.
Kahn, Zankou's demon advisor, is disturbed Zankou is so obsessed with the sisters – why not just keep trying for the nexus? Zankou disagrees, and sends Kahn to gather ingredients for a power-stripping potion. When the sisters make a play for the book, Zankou steals Phoebe's powers. Speaking of obsessions – Sheridan is furious Darryl never told her about the sisters, and tells him he needs to come in and help Homeland Security. Failing that, he better not warn the sisters.
The Elders tell the sisters they must regain the Book, if only to destroy the nexus before Zankou can tap into it. Leo gives a stirring speech to rally the sisters. Piper decides to try to recruit more allies – she asks the Vampire queen to attack Zankou so they can regain the book. Never trust a vampire – she betrays them. With Phoebe's powers, Zankou foresees the attack and is waiting for them. He takes Piper's powers. On the Homeland Security front, Sheridan volunteers to take a hidden camera into the Manor – they have to let her in, and then she'll provoke them into performing magic. She wanders into the Manor, but finds it deserted. The Homeland Security chief warns her to get out, but she decides to check the attic. She finds Zankou, who barbecues her. Homeland Security sees this and decides to storm the house.
The sisters despair – there's no way they can defeat Zankou and survive, but maybe they can take him down with them. They show up at Papa Halliwell's house and drop off the boys and all the documentation for their lives, then say their goodbyes. Darryl has been honoring his wife's ultimatum and staying away from the Sisters. Leo shows up and begs him to make sure Sheridan stays out of the Manor. Darryl tearfully tells his wife he has to help.
Zankou finally breaks through into magic school, where the sisters are discussing one of Prue's long-lost powers. Zankou tries to take Paige's power, but finds he can't – he's attacking the sisters' astral bodies. The real sisters are in the manor, and they take the Book. They see Homeland Security arrive at the house. Daryl gets there in time to tell the agent not to send anyone in. The sisters try to draw up the nexus, but it's too late. Zankou draws it into him, and the sisters strike. They recite the spell to destroy the nexus, and take out Zankou with it. The vanquishing is like a bomb blast.
Homeland Security storms the house and find nothing alive. Darryl is devastated to hear the sisters had been in the Manor. Leo is frantic – he wants to get into the house, but the cops won't let him. He fears the worst. But three strange women pull him aside – it's the sisters, disguised. They staged their own deaths to get their lives back. Everyone thinks they're dead – Elders, Demons, cops – so they can finally live their lives. The sisters disguise Leo too. The Halliwell family walks off into the sunset. Darryl sees them go, and figures out what must have happened.