The Power of 3 has been destroyed. Prue is dead, but while Piper and Phoebe mourn and Cole is confronted by two demonic bounty hunters a young girl finds herself drawn to the Halliwells.
Phoebe and Paige must work quickly before Piper is tricked into giving up all of their powers when The Source taps into her brain, altering her perception of reality and placing her in a mental institution.
Cole's past comes back to haunt him when a widow tracks him down seeking vengeance for her husband's death. Meanwhile Piper and Leo test their readiness to become parents.
The Charmed Ones must protect the muses from a warlock who is trapping them into a magical ring and using their inspiration to make the Forces of Evil more powerful.
Leo takes Paige back in time to relive the events leading up to the car accident which killed her adoptive parents. Meanwhile two outlaw ghosts from the 1950's possess Phoebe and Cole.
While on jury service, Phoebe has a vision that reveals that the defendant is innocent of murder. As she tries to stall the trial, the rest of the charmed ones must try and find the real killer before sentence is passed.
Paige discovers that a 10-year-old runaway (guest star Alex Black) is a firestarter and being hunted by demon bounty hunters. So while they protect him they try to teach him how to use his powers for good rather than evil.
The Source breaks an age-old agreement between good and evil by stealing The Hollow, an ancient vapor which he uses to absorb Piper and Paige's powers.
Phoebe develops a case of cold feet over marrying Cole and casts a spell which brings a young innocent Phoebe and an old cynical Phoebe to the Manor to help her make a decision.
After 60 years of searching, two ghosts who fought with Leo in WWII come after him seeking revenge for old wounds. When they turn this wrath on his loved ones and kill Piper, Phoebe and Paige face the horror of losing another sister.
Piper and Paige team up with a magical Wizard to stop the coronation of a new Source, not realizing that the new head of the Underworld is Cole and Phoebe is his Evil Queen-to-be.
The new Source and his queen have to prove that they are truly evil by killing Piper and Paige in order to prevent a civil war breaking out in the underworld.
The Charmed Ones are visited by the Angel of Destiny who offers them a choice of destinies for vanquishing The Source: they can remain Charmed or choose to relinquish their powers and live normal lives.