Things go from bad to worse when it is revealed that this Stepford-wife-like "Oh-so-perfect" mother is in fact possessed by a demoness focused on kidnapping Piper's son Wyatt and using him in a plot with other demons to resurrect the Source of All Evil at Magic School; which the demons have forcibly taken possession of after the (believed and faked) deaths of the three Charmed Ones.
Meanwhile, Paige sees Dex with another woman, who turns out to be his ex-girlfriend who is a compulsive liar, and despite Phoebe's objections, interferes by masquerading as the woman looking and expecting evidence Dex is two-timing Phoebe.
She and Paige discover that an experiment with a captured demon created a deadly virus that is infecting the magical community, including Billie.
The Angel of Death returns to visit the Charmed Ones but they're shocked to learn that he's there for Leo.
Paige takes up a career as a police recruit, hoping fighting evil that way will fulfil her needs, but has to leave training to rescue Billie.
Hoping to lure the Charmed ones out of hiding, Haas, a young demon suspecting they've survived and wanting to take over the rule of the Underworld by taking their powers, uses the Alice's Adventures in Wonderland fairy tale to prey on victims.
Piper vanquishes both threats by dealing with the demoness—who has linked the two by her conjuration of the source which consequently was not as powerful and troublesome as the original incarnation of source because the magical link to the demoness gave it a new vulnerability.
Unaware that she is being watched, Billie jeopardizes the Charmed Ones' new lives when Agent Murphy of Homeland Security, who has suspected all along that she and the "cousins" are involved in supernatural activities and that the Halliwell sisters are not dead, spots her using her powers to save an innocent.
Wyatt's school play Cinderella brings out the competitive nature in Piper when her hand-sewn costume and parenting abilities are criticized by another mother.Paige gets the hots for one of her instructors and is happy to have to leave training to rescue Billie and begin not just one, but two new relationships, both of a much more satisfactory nature, though still wonders what to do for work.Looking for a new career path, Piper goes on an interview with a corporate recruiter, but is soon arrested when a background check reveals that the physical appearance she adopted was that of a model wanted for murder.Airing on Sundays at pm, the season consisted of 22 episodes and concluded its airing on May 21, 2006, only four months before The WB shut down to merge with UPN to form The CW.Paramount Home Entertainment released the complete final season in a six-disc box set on September 11, 2007.