After being presumed dead, the Halliwell sisters begin their demon-free existence with new identities: Phoebe is overwhelmed with visions of her future husband; Paige begins hearing her whitelighter call, which draws her to a mysterious young witch; Piper attempts to deal with her financial situation, the club and her children. Meanwhile, a brash young demon decides that he wants the Halliwell manor as a trophy and plots to kill Victor to get to it.

Billie jeopardizes the Charmed Ones' new lives when Agent Murphy spots her using her powers to save an innocent. Meanwhile, Phoebe's overnight trip with Dex comes to a surprising conclusion when Billie casts a spell to make her happy, a spell with unexpected consequences.

Wanting to return to her old career as a social worker, Paige's plans get put on hold, when her Whitelighter father, Sam, returns asking for her help with his charge. Meanwhile, Piper and Leo go to see a magical marriage counselor who thinks the best therapy is for them to walk a mile in each others' shoes - literally.

Agent Murphy gives the sisters their first Homeland Security case - searching through cold case files, where Phoebe and Billie discover a belt that gives Billie superpowers. Meanwhile, Piper and Leo are on the hunt for a band to play at P3; and Paige meets a handsome man, who happens to be her new charge's parole officer.

When a demon escapes from custody, Agent Murphy enlists the Charmed Ones to help, where they learn a government created virus is spreading amongst magical beings, that causes them to "hulk out". Meanwhile, Billie becomes infected with the virus and it's up to the sisters to find an antidote.