The Source breaks an age-old agreement between good and evil by stealing The Hollow, an ancient vapor which he uses to absorb Piper & Paige's powers. Meanwhile, Phoebe must allow Cole to help them, despite her having a premonition involving Cole sacrifici

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. Meanwhile, while Cole is horrified to find that The Source is now taking over his entire being, The Source's chief rival, who believes The Source is dead, is convinced by The Seer to kill The Charmed Ones in order to earn the allegiance of the entire underworld.

As Phoebe prepares for her wedding day, she is completely unaware that the Source has taken over Cole's body, a plot that will likely ruin the big event. Meanwhile, when the Seer tells the Source that if he can marry Phoebe in the ""dark way"", it will insure that their future son will be the most powerful, evil being ever.

Amongst newlyweds, Phoebe & Cole and already-married, Leo & Piper, Paige begins like a fifth-wheel but she continues her suspicions about Cole. Meanwhile, the Source plots to impregnate Phoebe with his evil spawn.

Phoebe tells Piper and Paige that she is pregnant, and that Cole is the father. Meanwhile, Piper and Paige team up with a wizard to stop the coronation of the new Source, unaware that it is Cole and Phoebe is soon to be his Queen of the Underworld.

Phoebe accepts her new role in Cole's life, but she still sets out to save an innocent after she has a premonition and even seeks her sisters' help in protecting the man. Meanwhile, Piper's heart doesn't seem to be in it as she prepares to defend her family against any new threats from the underworld.

The Seer plans to steal Phoebe's unborn baby so she can raise the child to become the next Source and prevent the throne from passing on to another demon. Meanwhile, the baby begins to take over control of Phoebe's body, which proves dangerous to Paige.

In his twisted attempt to win Phoebe's heart back, Cole casts a spell that alters reality, that eliminates Paige as a Halliwell and destroys the Power of Three. Meanwhile, Paige suddenly finds that her sisters have no knowledge of her existence and that past villians have come back to haunt them.