The sisters have to live under false identities to be free of demons. Each sister remains unhappy and eventually decides to return to their Charmed lives. Paige, however, begins helping a young witch named Billie, who eventually discovers the sisters' magical secrets but agrees to keep them under wraps in exchange for witchcraft training.
The sisters question themselves after Gideon's betrayal. Phoebe is such an emotional wreck that her boss lets her take a break and hires a ghost writer -- a man with whom she takes awhile to warm up to but eventually develops feelings for. Finally, darkness surrounds the sisters in the form Zankou, a demon who had been locked away by The Source.
Season 4 brings big changes in the lives of the Halliwell sisters. As they face the loss of a sister, Paige Matthews arrives - half sister to the Halliwells. As Piper and Phoebe cope with the death of their sister, they learn to accept Paige and teach her the ways of witchcraft all while perfecting the use of their own growing powers.
The sisters continue to balance their personal lives with their magic as they begin to gain more control over their powers. The sisters also find themselves traveling to both the past and the future throughout the season, in addition to facing their own family history when they are forced to destroy the demon that was responsible for their mother's death.