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.

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.

With the intention of helping his parolee get a loan, Henry, along with Paige, go to a bank but instead the parolee decides to take everyone at the bank hostage. Meanwhile, Phoebe and Piper have their hands full when, during his third birthday party, Wyatt turns three of his toys into real people.

During Chinese New Year, a demon attempts to steal a mystical wooden staff, that's protected by the Zodiacs and they enlist the aid of Piper. Meanwhile, Phoebe enjoys her new place by throwing a housewarming party that gets out of control; a monk teaches Billie how to use her power of projection to find her sister; Paige tries to get through to Henry about her magical abilities.

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.

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.

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.

Paige accidentally summons a medieval knight, who believes Paige is the love of his life. However, the knight is under the influence of an evil sorceress.

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.

While attempting to take over the Underworld, a young demon plots to lure the Charmed Ones out of hiding, but when Billie stumbles onto his plot ,she becomes one of his victims instead.

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.

When her parents come for a visit, Billie accidently transforms them into assassins and also manages to contact a demon who is posing as a human. Meanwhile, Piper attempts to continue her life without Leo; Paige tries to make a connection with Henry; Phoebe tries to find a way to have her own life.

Phoebe, in an attempt to move on with her own life, signs a lease for a new apartment, and Paige considers moving in with Henry. However the sisters are forced to remain under the same roof when a demon shrinks them and traps them in a replica dollhouse of the Manor.

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.

Piper, Phoebe and Paige come to the aid of Mylie, a Mermaid-turned-human, when she shows up looking for their help after a pact she made with an evil Sea Hag begins to go drastically wrong. Meanwhile, Phoebe attempts to divorce Cole, until he shows up claiming to want her back, Paige, attempts to juggle her new position as a full fledged Social Worker, as well as being a Charmed One, and Piper must protect her unborn baby, and face her fear of water.

When Phoebe must constantly save the life of her new boyfriend, a warlock shows up from the future, claiming that future Cole sent him in order to kill the boyfriend before Phoebe's dies instead. However, present Cole cannot allow this and tries to help the sisters protect Miles, but when the warlock decides to work on his own agenda, by stealing the Book of Shadows, it results in the death of two of the Halliwell sisters. The survivor must decide whether going back to change the past is the right thing to do.

When a demon attacks and kills one of the three nympths that protect a lake, the Charmed ones try to help. However, once the demon is destroyed, the nypmphs decide Paige should replace the fallen nymph, and they won't take no for an answer.

In order to get close to baby Wyatt, the Crone steals one of the senses from each of The Charmed Ones, in an attempt to fool the child.

With Piper away at magic school and Phoebe without her active powers, overworked Paige conjures Mr. Right for stress relief but, unknowingly, releases his evil twin, Mr. Wrong.

The Avatars enlist Leo to protect the Seer because she has information that could help them destroy the demons. Meanwhile, Brody reveals a secret to Paige, and Phoebe and Darryl continue to investigate Brody.

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.

With Piper growing more concerned that Leo will never return, Prue and Phoebe try to save a little girl and a fairy princess from evil Trolls. When Prue and Phoebe need Piper's help, her concern with Leo causes a spell to backfire, placing the girl in danger.

On Halloween, the sisters are pulled back in time to the 1600's to save a witch and her soon-to-be-born child from the hands of an evil witch who wants to raise the child evil. The sisters later discover that this situation may have more personal implications than they first imagined.

When Prue discovers that her ex-boyfriend is being led down the path to becoming a demon, the sisters must risk their lives in an underworld wrestling ring to save his soul.

Piper, Phoebe and Paige are shrunk to a height of five inches when they walk into a trap set by a demon named Gamil.