After the devastating events of the battle in the last episode, both Piper and Billie go about trying to get their sisters back. Piper is reunited with Leo and together they enlist Coop's help to go back in time and save their family.

The Charmed Ones find themselves stuck in the Underworld attempting to restore the reputations that Billie and Christy helped tarnish. Piper sees Leos ghost and he gives his approval for the sisters to team up with the demon Nomed. Phoebe unintentionally breaks Coops heart and Paige offers her support. Billie, Christy and the Charmed Ones realize separately that they must conjure The Hollow, the most powerful force known to man, in order to defeat one another, leading to a devastating battle.

Convinced that The Charmed Ones are too self-involved to protect the "Greater Good," Billie and Christy team up to destroy their reputations in the magical community. Calling upon her intimate knowledge of the sisters, Billie uses her spells to make the girls seem like they only care about themselves. Christy, with the urging of an immortal demon, amps each spell up to dangerous levels. Phoebe obsessively lusts after Coop, Paige is unable to hear her charges' calls for help, while Piper turns into a perfect 1950s housewife. When their approval rating hits rock bottom, The Charmed Ones are forced into hiding in the Underworld.

Suspecting that Billie and Christy are the , Ultimate Power,, Phoebe and Piper begin to formulate a plan that will provide the answers they need to get Leo back. Meanwhile, Paige saves her new charge, Mikelle from two Darklighters, and Christy traps the sisters in a dreamstate in order to prove to Billie that each of their , inner-truths, are driven by selfishness. Later, Billie must decide if she will team up with Christy to dethrone The Charmed Ones.

Coop tries to find the perfect love match for Phoebe, who has to choose between a mortal or someone magical. Coop later realizes he has fallen for Phoebe, just as she decides she wants to be with a mortal. Meanwhile, Paige finds it difficult to balance married life to Henry and her responsibilities as a Charmed One. Piper tracks the down the demons who killed Billie and Christy, 's parents and interrogates them in her effort to prove they are connected to the Ultimate Power.

After Paige and Henry leave for their honeymoon, Cupid "Coop" takes Phoebe on a journey through her past romances in an attempt to revive her excitement for love. Meanwhile, a group of magical teens, who are protA©gA©s of Leo, come to the manor seeking refuge from demons that have overtaken the Magic School, forcing Piper to take charge. Billie and Christy's parents come to town for a visit, but Christy refuses to see them in order to test Billie.

Piper organizes and engagement party for Paige and Henry, but the wedding is put in jeopardy when the couple begins to get cold feet. Phoebe notices a strange man following her, and soon discovers that he is Cupid. Meanwhile, a demon kidnaps Christy in order to lure The Charmed Ones into attacking the Triad and prevent them from taking over the Underworld.