Cole has a nightmare in which he has to tell Phoebe the truth about himself and morphs into Belthazor. He wakes up to find a member of the Triad in his room. He conjures a knife into Cole's hand and threatens to kill him if he doesn't kill the Charmed Ones.
The sisters meet at P3 and discuss Belthazor. Since he is an upper-level demon, they need to somehow get part of his flesh to make a vanquishing potion for him. Phoebe stares off into space, expecting Cole at any moment. Cole finally shows up and tries to pull Phoebe aside. The sisters have a dozen scheduling conflicts and try to palm off their various tasks on each other. After Piper and Prue leave, Cole claims an insight on how to win a big case, and leaves Phoebe. He heads out back, and tells his shadow to inform the Triad he's figured out how to kill the sisters.
At the manor, the sisters are eating breakfast when Belthazor barges in. Phoebe levitates and kicks him. "Belthazor" recovers and throws an energy ball, but Piper freezes it just in time. Prue astral-projects and kicks "Belthazor" from behind. Just as "Belthazor" recovers, Piper slashes him with a knife, and he reveals himself to be Leo in a glamour-- it was all a drill. The sisters have believed for some time Belthazor would be bold enough to attack them at the manor and had been rehearsing for such an attack. Cole confers with Andras, the Demon of Rage. He plans to use Andras to divide the Charmed Ones. Cole tells him that the Charmed Ones' powers are tied to their bond as sisters, if Andras can break it, Cole believes it will be easy to attack them. He wants to go after Phoebe first, since she's the youngest and most vulnerable.
Phoebe is coming home from class and runs into Cole in the parking lot. He apologizes for walking out on Phoebe the night before, and asks her out. She says she can get Piper to cover for her. As Phoebe drives away in Prue's car, Cole gestures and a gas line develops a leak.
Piper is serving refreshments for a homeowners' association meeting, and is somewhat perturbed that she has to constantly put off a doctor's appointment to help them. The neighbors bicker uncontrollably. Phoebe finally comes home and asks Piper to take her place at the meeting. Piper resents being burdened in this fashion. She wants Leo to help, but he's called away on another assignment.
Cole, outside in his car, calls for Andras. He tells him to infect Piper first. Andras is confused, but Cole tells him that he plans to have Prue infected next, and then they'll blame Phoebe for everything. Andras notices Cole doesn't seem too excited about what will be a major coup. Cole picks up Phoebe. Andras infects Piper with rage. Piper angrily throws her bickering neighbors out.
Cole and Phoebe have dinner at a salsa club. Phoebe talks a bit about her past, but Cole isn't willing to do so. Phoebe wants to dance, but Cole tries to beg out, claiming to be a bad dancer. However, Phoebe persuades him to get up for a slow dance.
Prue had a photo shoot scheduled at P3, but was unable to make it because her gas tank was too low--not knowing Cole ruptured it. Prue tries to get another time, but Piper snatches Prue's cell from her hand and cancels it. She is also angry at Prue for leaving her equipment laying around, and throws one of her lenses to the floor. Just then, Andras fills Prue with rage. Prue yells back at Piper and smashes a blender on the floor.
Cole brings Phoebe home. They start to kiss, but Cole sees Andras out of the corner of his eye. Phoebe arrives to find Prue and Piper yelling at each other. Phoebe tries to calm them down, but they turn on her. Andras infects Phoebe with rage, and she starts yelling back. Phoebe had been wearing Piper's earrings and Piper takes them off of her. Phoebe's rage boils over, and she kicks at Piper. Piper ducks and shoves Phoebe into Prue. Prue shoves Phoebe into a chair. Phoebe grabs one of Prue's cameras and throws it at Prue, who deflects it back at Phoebe. Phoebe levitates out of the way, and Piper freezes the camera in midair. The camera unfreezes and breaks against a picture. The sound of the camera breaking jars the three out of their rage, and a now-sullen Phoebe walks out. The triquetra on the Book of Shadows separates.
Prue and Piper are sweeping up the shattered camera when Leo orbs in. He tells them that "they" had felt their fight, and the Power of Three no longer works. Prue and Piper don't believe him, but to prove it Leo drops a glass bowl. Piper tries to freeze it, but can't before it shatters on the floor. Prue tries to telekinetically sweep up the pieces, but can't. Leo tells them that since they used their powers on each other, it severed their bond as sisters and they need to repair it fast in order to get their powers back.
Phoebe goes to Cole (who as Belthazor is chanting in a demonic language when she knocks). Phoebe is in tears and collapses into Cole's arms. Prue and Piper can't even scry for her. Leo finds Andras in the Book of Shadows. They realize that Andras boiled over some long-seething disputes.
Phoebe is still distraught over her fight with Prue and Piper, and Cole comforts her. He offers to get a tissue, but actually goes for an athame. He pulls it as they kiss, but cannot bring himself to harm Phoebe. In time, he tells her to go home and reconcile with her sisters. After she leaves, Cole finds Andras in his apartment. Andras taunts Cole for letting his human half develop feelings for Phoebe, and goads him into becoming Belthazor. Andras possesses Belthazor and heads for the manor.
Prue calls around, but can't find Phoebe anywhere. Just then, Phoebe comes home. All three make apologies. Belthazor/Andras bursts in. Prue tries to blow him back out the door and Piper tries to freeze him, with no success. Leo cracks a chair over him, but Belthazor/Andras punches him aside. Prue tells Piper and Phoebe to flee, but Piper and Phoebe wants to fight him together. At that moment, the triquetra rejoins. Prue flings the knife out of Belthazor/Andras's hand. Belthazor/Andras hurls an energy ball and Prue deflects it back at him, ejecting Andras. Belthazor turns on Andras and finishes him with an energy ball. The sisters take positions as before. Phoebe levitates and kicks at Belthazor, but the force of her own kick knocks her to the floor. Belthazor throws his athame, but Piper freezes it. Prue astral-projects and kicks Belthazor from behind. Piper unfreezes the athame and gashes off a bit of Belthazor's flesh. Prue flings him through a conservatory window. Belthazor morphs into Cole, badly wounded, and shimmers away.
The sisters meet at P3, where Fastball is playing. The bickering neighbors have settled their differences.
The Triad summons Cole. Apparently rumors had been brewing for some time that he'd developed feelings for Phoebe. One raises a fireball and allows Cole one last statement -- which he makes by killing the Triad.