Phoebe, disappointed in Cole, is adding a page to the Book of Shadows about his human form, alongside the existing page on Belthazor. Prue tries to comfort her. Piper hides in the basement, and blows up Christmas ornaments while struggling to control her new blasting power. Neighborhood dogs begin barking and even Kit seems disturbed. Meanwhile, a man grieves for his deceased wife, and his dog starts barking; the walls shake, a white-haired female figure enters through the window, screaming, and the man dies in agony as her scream bursts his blood vessels.
The next day, Prue tells Phoebe of the man's death, and she has a premonition about a young woman dying the same way. Phoebe was still writing about Cole and suspects that he is responsible, but Prue doubts it, not realizing that the premonition came from the entry behind Belthazor's page, which was a page about Banshees. Still, the two prepare their vanquishing potion and summon Cole with the spell from the Book. The spell fails, but angers Cole enough to turn him into Belthazor.
Piper tries yoga meditations to control her power. Leo orbs in and startles her, causing her to blow up her tape player. He reassures her that if the Elders didn't believe that she was ready for the new power, then she wouldn't have received it.
Prue and Phoebe go to the scene of the man's death. The police think he was murdered. Phoebe tells the inspector on scene that she and Prue are witches. The inspector, thinking that she was being funny, leaves. Prue definitely thinks that the death was supernatural.
Cole visits an alchemist, worried about the sisters' apparent attempt to vanquish him. He is also trying to permanently suppress his human half. The alchemist puts a spell upon Cole's blood so he will resist the potion.
Prue points out the page next to the one that Phoebe is writing: it's about a Banshee, a demon that feeds on pain. Leo describes the Banshee in detail. Prue says that it explains the shattered glass and bursted blood vessels, pointing to Phoebe that it really isn't Cole. Piper suggests wearing earplugs. The Book gives no vanquish for a banshee, but it does give a tracking spell. Phoebe and Piper cast the spell on Prue, which inadvertenly turns her into a dog. Prue-as-a-dog hides under the bed, and Phoebe keeps trying to get her out by making calling noises. Prue eventually comes out from underneath the bed, proving she still has some of her human understanding intact. Phoebe and Piper believe the spell to have backfired, but the outcome makes sense to Leo: dogs can hear a banshee's call, and track her. When the banshee is found and vanquished, Leo thinks, Prue should return to her human form. Meanwhile, they hear glass shattering and barking from the kitchen. Prue-as-a-dog's mind is becoming more and more dog-like as she follows her newly transformed instincts and chases Kit around the house. Leo, after admitting of being scared of Prue, orbs off to the Elders to ask how to defeat a banshee, but suggests Piper try blowing her up, something she is unsure she can do, due to her lack of control over that power.
Prue-as-a-dog runs out the door, apparently after the banshee. Piper and Phoebe follow, only to realize she just had to take a dump. They then argue about who has to clean up Prue-as-a-dog's poop with a plastic bag. Prue, despite her doggy instincts, is still embarrassed at having to relieve herself outside. After hearing lots of dogs barking and Prue-as-a-dog running off, Piper and Phoebe forego poop scooping to follow her again. The three find the young woman, a teenage runaway calling her family from a telephone booth. The banshee attacks, but the sisters arrive just in time. Piper blasts the banshee, who retreats. Prue-as-a-dog pursues the banshee, but is hit by a car. Prue is not seriously injured; the driver of the car comforts her, and takes her into his home.
Piper worries both about Prue, from not knowing where she is, and about Phoebe, who heard the banshee's scream. Phoebe reassures her that at least they saved the girl. Piper tells Phoebe that the banshee zeroed in on her, and banshees seek out people who are in great pain. Phoebe thinks that it's ridiculous. Piper tells her that she's in denial. Leo returns, and now he is extremely worried they escaped from the banshee as he explains banshee's are formally witches. It later shows a banshee's scream normally has no effect on a witch, but if she is experiencing great emotional pain it will turn her into a banshee. The banshee attacks Phoebe in the attic, zeroing in on her grief for Cole. The banshee, surprised that Phoebe isn't dead yet, stops screaming. When Piper and Leo rush in, the Banshee looks as if she is going to scream at Piper, who blows her up to shut her up, but Phoebe on the floor lies flat and transforms into a banshee.
Piper is by herself, now that Prue is a dog and Phoebe is a banshee and even more so after Leo warns her: if Phoebe kills anyone, she will be a banshee forever. Piper "loses it" and accidentally blows up Grams' sewing machine because she was tired of Leo telling her to relax, but he, again, manages to calm Piper. {C}Finally, Piper knows what to do.
Phoebe-as-banshee stalks a young woman, who thinks that her date has stood her up; but the woman meets her date, and Phoebe screams in frustration rather than to kill.
Prue-as-a-dog wakes up to find herself in the home of the guy who hit her with his car, a journalist, letting her drink from his imported beer collection. Phoebe's scream draws her attention, and she barks to be let out. She runs off, with her caretaker putting fliers up to find her.
Piper grabs the vanquishing potion and summons Cole. Cole claims not to love Phoebe and refuses to help, telling them that he doesn't do good deeds anymore. He also claims that his love for Phoebe died out when Phoebe gave up on him. Piper, at Leo's urging, throws the potion, but the Alchemist's spell protects him. Prue-as-a-dog runs into the manor, barking, and Phoebe-as-banshee follows. Phoebe attacks and screams at Cole, driving him to such pain that he becomes Belthazor. Belthazor grabs Phoebe and shimmers away.
Phoebe and Belthazor fight desperately at the mausoleum. Belthazor turns back into Cole and tells Phoebe that he loves her, in tears. Phoebe, surprised, screams. Prue-as-a-dog hears Phoebe's scream and leads Piper and Leo there. Phoebe returns to her normal form. Her recovery also turns Prue back into a human, though her hip hurts from being hit (and her head is covered in fleas). Phoebe still wants nothing to do with Cole, but Cole tells Phoebe that they are both hurting, which was what lead them into fighting. He also tells her of Raynor's plan to turn him by making him kill a witch against his will. He shimmers away, leaving Phoebe undecided about him. Prue is relieved to be human again, not having to worry about the embarrassment of peeing outside or being distracted by every taste and smell around her.
Back at P3, Phoebe believes there's still good in Cole and that she can bring him back. Meanwhile, Prue has a date-- with the guy who cared for her when she was a dog.