Phoebe takes a sabbatical and is uncomfortable when she learns her replacement Leslie is a man. Darryl and Sheridan investigate Chris' disappearance. Leo has been relentlessly chasing Barbas for two months, and an unknown power tries to reach out to both of them. Worried when Leo almost kills another Elder, Phoebe and Paige take it upon themselves to vanquish Barbas once and for all, meanwhile the latter gathers an army and goes after baby Chris. Two Hindu Gods possess Piper and Leo.
Leo is obsessed with finding Barbas, who had helped Gideon in his attempt to kill Wyatt, and Barbas is taking advantage of his obsession by constantly taunting him through his fears. Leo meets with another Elder, Zola, and almost electrocutes him, believing that Zola is covering for Barbas. Zola comes to the sisters, his robes still charred from Leo's attacks, and asks for their help; if Leo kills another Elder, he'll have to be reborn and work his way up to Whitelighter status once more. Zola says the Elders believe a major threat looms and they can't lose another of their number. Leo is flipping through the Book of Shadows when he sees a ghostly face, which urges him to go after Barbas. Piper walks into the attic, but she doesn't see the face. Barbas also sees the face, which urges him to go after baby Chris; Barbas thinks this is a fine idea.
The sisters have been invited to a Hindu wedding, and Paige, talking to Phoebe, suggests talking Leo into accompanying Piper. This is a better way to get him away from his pursuit of Barbas, and perhaps bring him and Piper back together. Paige stays behind with Wyatt, while Phoebe, Piper and Leo go to the wedding with Chris. Darryl and Inspector Sheridan serve a summons on Phoebe regarding the disappearance of Chris. As the marriage is sealed, two spirits enter Leo and Piper and, much to their surprise, Piper sprouts four extra arms.
Piper and Leo begin behaving differently, dressing in traditional Hindi clothing and appearing very much in love. Leo is no longer concerned with Barbas. Piper is able to multi-task perfectly thanks to her extra hands.
Phoebe feels like she's in a rut and Elise suggests she take a two-month sabbatical; she will hire a ghostwriter to continue writing her column. Phoebe meets the ghostwriter, Leslie. She is surprised to see that Leslie is a man, and kisses him within moments of meeting him due to the contagious effect of the spirits that entered Piper and Leo. Still, she is skeptical that a man can write her column as well as a woman.
Paige consults the Book of Shadows and finds what's got into Leo and Piper: Shakti, the Goddess of Creation, and Shiva, the God of Destruction. They are invoked at weddings, as symbols of the ultimate lovers, but if they consummate their love again the universe will be destroyed and recreated. Paige and Phoebe send Leo after Barbas in order to keep him separated from Piper. He disappears in a burst of lightning.
Barbas has gathered a gang of demons and explains his plan. He wants them to attack Chris, so that Leo will make a fatal mistake in his rage and the demons can take on the unprotected Charmed Ones.
Paige goes to Magic School looking for information on Shakti and Shiva and finds it being closed down. With Gideon dead, there's no one to run the school.
Barbas's minions attack at the manor, but they were not counting on Shakti. The six-armed Piper easily defeats them with lightning and energy balls. On discovering Barbas, she blasts him with lightning and he flames away. Paige and Phoebe try to keep Leo from finding out, but he finds the nursery in shambles.
Darryl and Sheridan break the door of the manor and try to arrest Phoebe, who did not answer the summons, but Leo gestures and blasts Sheridan into a wall, injuring her. He then disappears in a flash of lightning. When Sheridan comes to, she remembers that she is there to look for something, but doesn't remember what. She doesn't remember being attacked, and Phoebe covers, by saying that they are remodeling, and that Detective Sheridan had slipped.
Leo again attacks Zola, taunted by Barbas, and kills him this time. Afterwards, he feels only remorse. Piper assures Leo that "nobody else has to know." Paige casts a spell and expels Shakti and Shiva from Piper and Leo.
Since Piper wounded Barbas, Paige scries for him using his blood. Paige and Phoebe track him to his lair. Paige throws a potion and Barbas says he'll be back before he explodes. "Fear always comes back," he screams, as he falls into a pile of dust...again. Before dusting out, he cries, "You set me up!" to an unseen entity.
- Batman Gambit: Barbas leads an attack on Chris. He doesn't care either way about the kid, but doing this gets under Leo's skin and provokes him into doing something stupid. Afterwards, Leo is off Barbas's back and the sisters are without a powerful bodyguard.
- Big "NO!": Piper when Barbas moves in toward Chris.
- Bittersweet Ending: Barbas is dead (again), Phoebe accepts her new ghostwriter, and Piper decides to "brave the big bad world" with her kids. However, Leo's angst isn't going away, and he's approached by the new power.
- Dark Secret: Leo kills Zola unprovoked. Piper agrees to keep it a secret from the Elders.
- The End... Or Is It?:Leo: What are you? What do you want?
Demon Head: What do we want? We want you!
- Happy Ending Override: The last episode ended rather bittersweet, with Chris dying, but everyone else safe and welcoming the new baby to the family. Now, it's two months later. Leo's become a darker figure obsessed with killing Barbas and lashing out any possible threats to his family, while Piper is too afraid to take the kids out of the manor. The episode also highlights how a new threat is gaining prominence.
- Heroic BSoD: Leo starts out this way, and it gets progressively worse.
- Mama Bear: Piper fends off the demon attack on her own.
- Papa Wolf: Leo, but he takes it the point of obsessiveness and playing into Barbas's hands.
- Reality Ensues: Last season ended with quite a few questions about Chris from the outsider's perspective (e.g. how he broke out of jail, has no records, a body that can't be found). Sheridan reminds Phoebe that the police haven't forgotten these things and want answers now.
- Reincarnation: Zola says this is what'll happen to Leo if he doesn't stop—"recycled" and starting over.
- Sadistic Choice: Darryl doesn't want to help the sisters anymore, but he doesn't want to help Sheridan, either. He just wants out, period, but Phoebe tells him he'll have to pick a side sometime.
- Time Skip: It's been two months since the last episode.
- Took a Level in Badass: A temporary one, as being possessed gives Piper extra arms and new active powers.
- We Will Meet Again: Though this ended up being Barbas's last appearance on the show.Barbas: You know I'll be back. Fear always comes back!
- Why Did It Have to Be Snakes?: Barbas plays on Leo's fears of the threats against his sons, as well as the fear that vanquishing him won't end the pain. The demon head actually does the same, too.Barbas: He's after your boy. I'm after your boy. We're all after your boy!
- You Have Outlived Your Usefulness: The entity was using Barbas to further Leo's descent. Once he succeeded, hehad no further use and was abandoned to the sisters.