Billie and Christy are cleaning up after the fight in the attic. Billie is willing to help Christy kill the Charmed Ones, but still doesn't like it and is doubtful that they have enough power to take on the most powerful witches of all time. Christy suggests they brew up the Charmed Ones' most powerful vanquishing potions when the Charmed Ones show up again. Just then, Coop flashes in looking for Phoebe. Billie and Christy say they're looking for her as well. Coop tells them that when he last saw her, they were talking when she suddenly fell under a spell. He exchanges a skeptical glance at Billie and flashes away.
The Charmed Ones huddle in front of a fire. Paige jokingly suggests giving up, but Phoebe says she's willing to fight to get their lives back. Piper wonders if Phoebe is really willing to kill Billie and Christy, since she was closest to them. Phoebe replies that as far as she's concerned, they're no different than demons.
The demon Nomed appears at the newspaper, claiming to be an admirer of Phoebe's. Phoebe has not been at work for days and Elise is worried, but she is skeptical of Nomed and asks him to leave. He and his friend Zohar realize the Triad are after the Charmed Ones. Nomed suggests to Zohar that they seek the Charmed Ones' help to destroy the Triad for good.
Wyatt and Chris are staying with their grandfather. Coop flashes in and Victor doesn't recognize him, but Coop convinces them that he's not a threat. Coop says he's in love with Phoebe; Victor is suspicious, but Coop asks Victor to call for him if he sees Phoebe again.
The Charmed Ones enter the attic, finding no one present, and prepare potions to vanquish Billie and Christy. They go downstairs and confront Billie and Christy, who also have potions. Piper and Phoebe start to throw their potions, but Paige holds back, and tells her older sisters to stop. Billie and Christy seemingly teleport away. Paige tells Piper and Phoebe that they were merely mirages created by Billie's projection power. Just then, the real Billie and Christy enter with potions. Both sets of sisters throw their potions, which collide in midair. The resulting explosion blasts the Charmed Ones through the window out of the manor and Bille and Christy into the staircase. Piper is knocked out and Christy is injured. Paige orbs her sisters to Phoebe's condo. Just as Paige and Phoebe are about to tend to Piper, Nomed and Zohar knock them both unconscious. When they come to, the two demons tell them that the Triad is alive again. The two demons drop another bombshell--the Triad are the ones backing up the Jenkinses; even as powerful as they are, they aren't nearly strong enough to take on the Charmed Ones alone. They offer their help. Nomed tells them that he worked with the Triad before, and knows what they're thinking. The Charmed Ones are skeptical, but agree to accept their help. Piper sees a faint apparition of Leo.
Nomed and Zohar shimmer to Magic School. They overhear Billie and Christy figuring out what to do next. Billie wonders if killing the Charmed Ones is such a good idea; she's afraid of losing Christy. Christy assures Billie she isn't going anywhere. Dumain walks in. After hearing what happened, he tells the Jenkinses to go back to the manor to keep the Halliwells from reclaiming it, and assures them they'll be better prepared when the Charmed Ones strike again.
The Triad chastises Dumain. Dumain says that so far, they've managed to fight the Charmed Ones to a draw--something no evil being has ever done. The Triad thinks this isn't enough, saying that they have to be eliminated before the next generation becomes too numerous and too powerful to stop. They tell Dumain to have Billie and Christy summon the Hollow. Dumain is skeptical, saying that the Hollow is too risky. This task will require Charmed power--power that can only be obtained through one of Piper's sons. Unknown to Dumain and the Triad, Nomed and Zohar are listening in.
Phoebe scries for Billie and Christy while Paige and Piper prepare more potions. Phoebe finds the Jenkinses at the manor. Piper is convinced she saw Leo--and that it isn't a good sign. Just then, Nomed and Zomar shimmer back to the condo and tell the Charmed Ones of Dumain's plan to summon the Hollow. Piper suggests that the Charmed Ones to get the Hollow before Billie and Christy do. Paige is skeptical, remembering what it did to The Source and Cole, but Piper is convinced that the Jenkinses are trying to steal the Charmed Ones' powers. In the midst of the discussion, Coop flashes in and Phoebe pulls him aside. She tells him she's too overwhelmed and that he should leave; he flashes away.
Dumain shimmers into Victor's apartment and Wyatt raises his force field bubble around himself and Chris. Dumain tells Wyatt that he has to orb to the manor to help Billie save Piper. Wyatt orbs out, and Dumain shimmers out behind him. Chris starts crying. Dumain shimmers into the attic just as Wyatt arrives, and tells Billie they have to summon the Hollow. Billie is frightened at the prospect, but Dumain tells them they have to do it in order to keep Wyatt and Chris from turning evil.
Paige and Phoebe think summoning the Hollow is too risky, but Piper argues they can vanquish Billie and Christy and say the spell to send it away before it infects them. The alternative, she says, is letting the Jenkinses get it--which will mean certain death. Nomed and Zohar say they have to vanquish the Triad as well--and the Hollow will give them the power to do it. When Piper wonders if they'll have to worry about renewed demon attacks, Nomed says that the Charmed Ones have severely decimated their ranks over the past eight years. Apart from the Triad, the few demons that are still alive are not nearly strong enough to take on the Charmed Ones head-on, and they'll only be able to regroup when the next generation of witches takes over. Piper sees another apparition of Leo, and decides to summon the Hollow.
Billie doesn't like the idea of using Wyatt to help them summon the Hollow, but Christy is all for it, saying the Charmed Ones caused the situation in the first place. Billie decides to go along. She and Christy, holding hands with Wyatt, say an incantation to summon the Hollow. The Charmed Ones summon the Hollow in the same moment.
Dumain tells Billie and Christy to take Wyatt's powers so they can be evenly matched with the Charmed Ones. Just then, Chris, at Victor's urging, orbs Wyatt back home. Billie and Christy look threateningly at Dumain, who shimmers away just as Christy shoots fire at him from her eyes.
Piper tries to blast Nomed and Zohar. They take cover on the porch, where Nomed tells Zohar to sacrifice himself in order to ensure the Triad perishes. Nomed pushes Zohar out in front and shimmers away. Zohar throws an energy ball at Paige, but she merely absorbs it. The energy flows to Piper and Phoebe as well. They throw energy balls of their own at Zohar and vanquish him.
Dumain, worried, tries to warn the Triad about Billie and Christy. He fears that the Jenkinses will come after them once they destroy the Charmed Ones, since now they crave power. Just then, the Charmed Ones appear. Dumain sees the danger and shimmers away. The Charmed Ones vanquish the Triad with lightning. They orb to the manor, where Billie and Christy are waiting for them. Both sets of sisters are surprised to discover that neither have or need potions. The Jenkinses throw fire, and the Halliwells reply with lightning. The power is so strong that it blows the manor to bits, killing Phoebe, Paige and Christy. The Hollow returns to its containment.
In the wreckage of the manor, Piper regains consciousness. She finds Phoebe dead on the floor. The Angel of Destiny appears, and returns Leo, noting this wasn't the way the battle was supposed to end. Piper hears a moan, and thinks it's Paige; but she lifts the wreckage, and finds Billie. Piper, blind with rage, starts to beat up Billie, but Leo separates them. Billie runs away, and Piper tries to blast her, but Leo pulls her away.