Look Who's Barking

Piper is still having difficulty handling her new power of molecular combustion, blowing things up accidentally almost at random whenever she moves her hands, and worse, sometimes blows things or people up when she means to use her first talent Molecular immobilization (Freezing) and draws into retreat in the basement of the manor for the safety of all concerned, so far as she is concerned. Meanwhile, Prue and Phoebe hunt down a Banshee, a demoness who kills people by bursting their blood vessels with her shrieks after a pattern of serial deaths puzzles police. But while they find it, the Banshee attacks Phoebe, turning her into a Banshee as well, as she is sad and susceptible while still grieving over likely losing Cole. After their first unsuccessful hunt, when Piper and Prue consult the Book of Shadows for a counter, the spell the book indicates (opens to) a page (by itself, as it sometimes does) "To Counter a Banshee" which causes Prue to be transformed into a dog, forcing Piper to gain more confidence in her capabilities as a witch as the sole remaining human witch while teamed with her sister, the white dog, cooperatively striving to find Phoebe before she kills and permanently becomes lost to them. Prue as dog after a number of too late, partial leads, finally tracks down the right Banshee, and the sisters manage to save Phoebe. Piper manages to blow up the Banshee with her new power, bringing Phoebe to Cole, who still loves Phoebe and can't deal with the pain of losing her. Banshee-Phoebe tries to kill Cole by bursting his blood vessels as well, but Cole ignores the pain Phoebe's shrieks cause him and claims he was under a spell when he killed Janna, which eventually cures Phoebe.