The two remaining sisters Phoebe (Alyssa Milano) and Piper (Holly Marie Combs) are left behind to mourn the loss of their sisters and to contemplate their futures in their ancestral San Francisco mansion as series 4 begins.
Prue untimely death has seemingly greater consequences in the sister's battle with evil, as it renders them unable to call on the power of three.
But it isn't long before Prue's place is the taken by the Halliwell's half sister Paige (played by Rose McGowan), who like the late Prue, also possesses Telekinetic powers. Paige soon takes up a job as a social worker, helping her to contribute to the cost of running the sisters San Francisco manor and more importantly, allowing her plenty of opportunities to use her magical powers for the forces of good.
The loss of Prue could have been a major loss to the show, as she was undoubtedly one of the most popular characters in the show and a major reason for the shows massive success during the first three years of production.
However, the appointment of Rose McGowan as Paige proved to be a master stroke and both the character and actress soon became massively popular in their own right.
During Charmed season four, Phoebe's boyfriend Cole (Julian McMahon) successfully purges himself of evil and leaves town to become accustomed to his new found mortality. Cole returns to the show to rescue Paige and Piper from a demon named The Source (played by Bennet Guillory).
Despite successfully saving the sisters, Cole is forced to sacrifice his human form to the source, who in cohorts with a manipulative female demon known as The Seer (Debbi Morgan) manages to convince Phoebe into marrying Cole's doppelganger and Phoebe soon becomes impregnated with Cole's demonic seed.
Charmed season 4 concludes as the Angel of Destiny (Dakin Matthews) approaches the charmed ones and offers them a demon free life, providing they vanquish The Source and his demonic minions.
