At Magic School, the Charmed Ones (or so it seems) battle demons. The demon Savard appears and tells them they lack the Power of Three. The "Charmed Ones" morph into three skankily-dressed female demons--Pilar, Patra and Phoenix. They have spent the last eight years (five years for Patra) tapping into the Charmed Ones' powers.
Phoebe is getting ready to move to a new condo. Piper is trying to find out what threat they have to fight in order to get Leo back. Paige is due to have dinner with Henry that night and has finally gotten up the nerve to confess that she's a witch. However, he's having a bad day. Phoebe suggests calling in some magical help to soften the blow.
The scantily clad demons meet with Savard. They are trying to find a way to copy the Power of Three so they can overthrow the Slave King, a powerful demon who has enslaved their kind for centuries. They remember the doll house in the attic (Scry Hard) and propose to trap the sisters in it, believing it will allow them to channel the Power of Three. Savard shimmers into the attic and steals the doll house, just as Piper walks in.
Billie is in Phoebe's room with the Book of Shadows and the spirit board, trying to find her sister. As she and Piper are talking, Paige orbs the book downstairs. She conjures a fairy from the exposed page and asks her to restore various lost objects to Henry. Henry finds his keys, his wallet, his 49ers cap, and other lost objects. Several parolees have asked Henry for letters of recommendation, and Paige summons a muse to help him.
Piper calls Phoebe at work and tells her she's found Zakal, a wizard who might have some insight on how to get Leo back. Piper asks Phoebe to get some mandrake root; Piper plans to vanquish Zakal if he doesn't talk. Phoebe enters an elevator and is surprised by Savard, who waves his hand and knocks Phoebe out. Phoenix shimmers in and assumes Phoebe's appearance. Savard shrinks Phoebe and traps her in the doll house. "Phoebe" joins Piper and Paige in the kitchen and initially doesn't seem to know about the mandrake root. "Phoebe" reaches in her pocket and conjures a mandrake root.
Piper, Paige and "Phoebe" summon Zakal, and Piper blasts him across the room to get him to tell them about any threats he's foreseen against them. Just as he's about to talk, "Phoebe" throws her potion and vanquishes him.
Pilar and Patra fade into Savard's lair; they apparently watched "Phoebe" destroy Zakal. Pilar and Patra want to replace Piper and Paige, but Savard wants a potion from the Book of Shadows to vanquish the Slave King, and they need at least one real Charmed One to approach the Book. Savard decides to replace Paige next. He tells Patra to convince Piper that the Slave King is the threat.
Piper is somewhat upset that "Phoebe" vanquished Zakal so soon, and thinks "Phoebe" is in too much of a hurry to get to her condo. "Phoebe" is surprised to find Billie in the room, and asks how the search for Christy is going.
Henry managed to write reference letters, as well as a love letter for Paige. Just then, he has an emergency -- the GPS has gone down on his parolees. Paige summons Andrew O'Brian, a leprechaun, to give Henry some luck. As the leprechaun rainbows away, Savard shimmers in, knocks Paige out and traps her in the doll house, replacing her with Patra. Paige tries to orb herself and Phoebe back home, but can't. She tries to drop a rock on Savard's head, but only succeeds in loosening a few pebbles. Apparently, their powers have been greatly reduced, due to their small size.
"Phoebe" doesn't seem all that interested in Billie's search for Christy, and suggests she just give up. She heads out and runs into "Paige". The two fake sisters find Piper in the attic with the Book of Shadows, and "Phoebe" apologizes for not being herself of late. "Phoebe" and "Paige" tell Piper of the Slave King and suggest that finding him might help Piper find Leo. Piper leafs through the book, with "Phoebe" and "Paige" standing well back.
The leprechaun waits for Paige at the police station, and huffily walks out when he thinks Paige stood him up. He rainbows to the attic, and "Paige" tells him she was helping Piper. "Paige" sends the leprechaun back to the station. He grants luck to Henry and several cops come in with his missing parolees in tow. On top of it, he wins $10,000 in the lottery.
Piper finds the Slave King in the Book. She doesn't see how he'd know anything. "Phoebe" says there should be a vanquishing potion in the back of the Book. At that moment, the real Paige and Phoebe attempt the "Call a Lost Witch" spell. However, their magic isn't strong enough for it to work, though, Piper feels that someone is calling her. Out of nowhere, "Phoebe" punches Piper and "Paige" orbs her to the doll house. Pilar shimmers in and replaces Piper. The three start working on the potion to vanquish the Slave King.
The real sisters use the replica of the spirit board to contact Billie, sending the word "dollhouse". Billie goes to the fake sisters as they are making vanquishing potions. Billie thinks it could mean something, but the fake sisters don't sound interested. "Phoebe" tells Billie to leave, and "Paige" calls her a nuisance. Billie thinks it's a joke, but "Piper" tells her they're serious. "Phoebe" shoves Billie to the floor and suggests they get rid of her, and "Paige" orbs her to the front porch. The fake sisters assume their true appearances. They go to the Slave King and all three throw potions, vanquishing him.
Paige, with some effort, orbs a stalactite close to the doll house. The sisters manage to goad Savard into coming nearer to them. When he does, Piper blasts him, knocking him onto the stalactite. It impales him in the head, vanquishing him. The demons shimmer in. When they find out the sisters vanquished Savard, Pilar gets ready to blow up the dollhouse in revenge. However, the sisters insult them in an effort to get them to use their demonic powers, rather than channel the sisters' powers. The demons ready fireballs and Paige orbs the doll house back to the attic, just as they get ready to throw. They shimmer after them, and Billie uses a spell to switch them with the sisters. The sisters are free and the demons assuming their identities are in the doll house, shrunken. Piper blows up the doll house.
Paige, having dinner with Henry, puts on a magical light show and admits to him that she's a witch. While at first, she believes that she has scared Henry off, he lets her know that he's not afraid.
Phoebe finally moves out of the manor, and Piper says a tearful farewell.