While struggling with the grief of losing Prue, Piper and Phoebe mourn over the loss of the power of three. However, when Piper tries to contact Prue using the Book of Shadows, she and Phoebe discover that they have a half-sister named Paige. It doesn't take long for the Source to learn of Paige as well, and tries to kill her before restoring the Power of Three.

Still angered over Prue's death, Piper goes on a demon vanquishing rampage, ultimately putting Phoebe, Cole, and herself at risk. As they fight the demons called The Furies, Piper accidentally inhales some smoke that was released by the demons, resulting in her anger magnifying and becoming a Fury herself. It is only after going to Prue's grave is she able to let go of her anger. Meanwhile, Paige steals the Book of Shadows and uses it for her own personal gain at work after she and some co-workers get harassed by a boss.