As Coop realizes that he has fallen in love with Phoebe, she throws him for a loop when she wants to peruse love with a mortal instead of with a magical being. Meanwhile, as Piper tracks down the demons who killed Billie and Christy's parents, she begins to suspect that the demons and the sisters are somehow connected to the Ultimate Power. Paige turns to Coop for help with some issues she has in regards to her marriage to Henry. Christy tries to convince Billie that the Charmed Ones are out to get her.

In order to get Billie to fight the Charmed Ones alongside of her, Christy and the demonic world resort to deception in order to get the magical community to think the sisters are no longer using their powers for the greater good, and as a result, need to be stopped. As a result, Piper, Phoebe, and Paige have to hide in the underworld in order to come up with a plan to fight back. Meanwhile, the demons working with Christy reveal that the upcoming battle will not only destroy the Charmed Ones, but also Billie and Christy.