Paige learns the difficulties of dating a mortal when Henry becomes too involved in the magical world and is torn when another suitor arrives hoping to convince her to marry him so they can become the ultimate magical couple. Meanwhile, Billie finally finds her missing sister, Christy; Piper faces a romantic decision when she runs into an old flame and begins to wonder if she should move on with her life.

Piper organizes an engagement party for Paige and Henry, but the couple begin to get cold feet. Meanwhile, Phoebe discovers a strange man following her but soon learns he is actually Cupid; a demon kidnaps Christy in order to get to the Charmed Ones.

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 protégés 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.

Coop comes to the conclusion that he has fallen for Phoebe but she'd rather spend her life with a mortal. Meanwhile, Piper is on the hunt for killer demons; Paige finds it hard balancing life as a Charmed One with that of a married woman.

Piper and Phoebe devise a plan to recover Leo. Meanwhile, Paige rescues her new charge from a Darklighter; Billie is forced to make an important decision.

In an attempt to destroy the reputation of the Charmed Ones, Billie & Christy resort to trying to make the magical community see that the Halliwells only care about themselves. Meanwhile, Phoebe begins to lust after Coop; Paige cannot hear her charges' call for help; Piper becomes the perfect 1950s housewife.

Forced to hide from Billie and Christy, the Charmed Ones find themselves stuck in the Underworld. Meanwhile, Leo appears to Piper and offers demonic approval; Coop searches for Phoebe; Billie & Christy resort to summoning the Hollow to stop the Charmed Ones and the Charmed Ones do the same.

Piper & Leo, with help from Coop's ring, must travel back in time to change the events that lead to the deaths of Piper's sisters. Meanwhile, Billie uses her power of Projection to do the same thing; many familiar faces gather to help Piper in her time of need.