Paige suspects that Leo has erased Piper's memories of their relationship, but her attempted memory recovery spell accidentally causes Piper to lose all her other memories too. Phoebe and Paige go off to find Leo, but he is currently being held captive on Valhalla, an island controlled by amazon warrior women called Valkyries. Also, Phoebe becomes an Empath, and Paige is startled when she sees a dog turned back into a human.

Phoebe and Paige enlist Chris' help to go undercover as Valkyries, while the sight of Leo brings Piper's memories flooding back. While everyone else escapes, Piper decides to stay behind with Leo. Unfortunately, the angry Valkyries followed them through the portal back to San Francisco.

After young Wyatt mistakenly conjures a dragon, a neutral group known as The Cleaners comes to remove the child and erase any traces of his existence. The Cleaners' mission is to prevent human kind from discovering magic, and they will not risk failure. The sisters can sense that something is amiss, and use a spell to regain their memories and bring Wyatt home. Also, Leo assigns Chris a new charge.

Three evil sisters steal the powers and identities of the Charmed Ones, and the real Piper, Phoebe, and Paige must convince Chris of what happened. Meanwhile, Leo continues to search for answers about who sent him to Valhalla, and Piper realizes that Wyatt needs more time with his dad.

While at a new job, Paige falls for an attractive male witch named Richard Montana, whose family is engaged in a longstanding feud with another magical clan named Callaway. The spirit of Richard's dead first love isn't accommodating to Phoebe's plans to end the rivalry, and takes possession of her body. Also, Leo begins to question Chris' motives.

Feeling that the Charmed Ones are putting their personal lives before their responsibilities, Chris uses a demon named Gith to teach them a lesson. Gith creates alternate realities for each sister, where all three get their deepest desire fulfilled. However, if Piper, Phoebe, and Paige don't escape these delusions and face reality, they may not make it out alive.

In an attempt to save her boss's immortal soul , Paige goes behind her sisters' back and makes a deal with the demon intent on claiming it. Also, Piper learns that Wyatt has been sabotaging her dates, and Leo finds himself trapped in the distant past with Chris after an attempt at traveling to the future goes wrong.

The mythical Lady of the Lake appears to the Charmed Ones, asking for their help to protect the legendary Arthurian sword Excalibur. The sword still resides its stone casing, and soon dozens of magical beings arrive to try their luck at pulling the powerful object free. Piper finally pulls the sword out, but that leads to the arrival of a mysterious figure known as Mordaunt, who may have his own ulterior motives.

After vanquishing a Manticore, the sisters become temporary guardians to its half-monster offspring. Chris urges them to get rid of the child before it can lead to danger for everyone, but the Charmed Ones believe that they can raise him to be good instead of evil. When the baby's beastly father comes to retrieve him, things really get complicated.

A Phoenix named Bianca arrives from the future, with plans to forcefully escort Chris back to the future that he came from. It is revealed that Chris and Bianca are engaged, and that Chris was sent back to prevent Wyatt from turning evil. The Charmed Ones are powerless to stop his departure, but do slip him a parting gift. Also, Piper tells Phoebe and Paige to move in with their boyfriends, jeopardizing the Power Of Three.

Paige tries on a pair of her grandmother's old go-go boots, and finds herself transported back to the 1960's. While there, she meets a younger hippie version of Grams, who is obsessed with ridding the world of evil through the power of love. Piper and Phoebe go back to make sure she doesn't alter the timeline. In the present, Leo, Chris, and the spirit of Grams battle a slime that consumes all magic around it.

After saving Wyatt from a demon, Piper decides to swear off relationships and devote the remainder of her life to raising and protecting her son. Paige and Phoebe decide to conjure a magical Mr Right, in order to remind Piper what love is like. Meanwhile, Chris tries to use Mr. Right's influence to get the sisters to bind Wyatt's powers, but the child is kidnapped before they even have a chance to consider it.

Phoebe's boyfriend Jason sees the sisters using their powers, freaks out, and dumps Phoebe. Richard Montana casts a spell to try and rid himself of his family's negative karma, but accidentally sends evil spirits into Phoebe's body, leading a possessed Phoebe to try tohug Jason. Elsewhere, Piper and Paige try to vanquish what Chris tells them are the last significant demonic threats to Wyatt's future.

Gideon, Leo's old mentor at Magic School, asks the Charmed Ones for help finding out who at the school cast the spell that conjured up the deadly Headless Horseman. The Horseman is running around decapitating the faculty, and needs to be stopped before he claims more lives. Elsewhere, a shaman student named Enola sends Phoebe on a vision quest to the future, where she learns Chris' true identity.

Phoebe frees a seemingly kind genie named Jinny from her bottle, only to find out that she now has to take her place in captivity. Chris attempts to use Phoebe to wish for Piper and Leo to get back together and thus ensure his own conception, but Phoebe's new genie powers grant the request in an entirely too literal fashion. Richard is worried about losing Paige, and wishes for her to come back into his life.

Gideon makes a secret deal with the Darklighters to get rid of Leo, but the plan backfires when Leo and Piper are both inadvertently trapped in the realm of the dead. Meanwhile, Phoebe and Paige mistakenly believe that Leo and Piper have both beenhuged, and a worried Chris reveals that he must be conceived before the end of the night or he will cease to have ever existed.

While getting ready for her high school reunion, Phoebe is possessed by her wild teenage personality and hooks back up with the bad crowd that she traveled with in her youth. Things get worse when her former friend Rick uses her powers to commit a robbery. Also, Piper calls upon her father Victor for answers as to why Chris is avoiding her.

Piper is held prisoner by the Spider Demon, a creature that emerges once a century in order feed off of a powerful magical being. Chris is infected by the spider's venom during the attack, which causes him to begin mutating into a spider himself. It's up to Paige, Pheobe and Leo to rescue Piper from the spider's web, and reverse the effects on Chris. Also, Leo finally figures out why Chris resents him.

Phoebe and Paige are caught using their powers by an SFPD officer, and The Cleaners move to cover up the situation by framing the sisters' cop friend Darryl as a cuddled. The Charmed Ones plead with a council of good and evil magical beings to set Darryl free, but the fear demon Barbas turns the proceedings into a trial of the Halliwells. Leo and Chris team to rescue the sisters, but Phoebe doesn't emerge entirely unscathed.

With Piper away at magic school, and Phoebe stripped of her powers, a stressed out Paige brings back Mr Right for some quality 'stress relief'. Unfortunately, she also unleashes Mr. Wrong, who appeals to Paige's latent dark side. To save Paige, Phoebe goes undercover as one of Mr. Wrong's 'Demonatrixes'. Meanwhile, Chris gets arrested, and Darryl refuses to keep covering for the Charmed Ones.

Gideon is worried that the sisters are close to discovering his plot to corrupt Wyatt, and makes the Charmed Ones unknowing contestants on a demonic reality show called 'Witch Wars'. If a demon 'player' succeeds in hunting down and vanquishing a witch, they then gain her powers. Meanwhile, Chris tells the sisters that whoever is pursuing Wyatt will take him before Chris' birth.

Under the pretense of sending Chris back to his own time, Gideon traps Chris and Leo in a mirror universe where evil always wins in the end and good is useless. Phoebe and Paige travel there to try and rescue them, but encounter a good version of Barbas, and find themselves doing battle with their own dark sided doppelgangers.

Unable to vanquish their own counterparts, Phoebe and Paige return to their own world, only to discover that it has become too saintly and every infraction is now a capital crime. The travel between worlds erases Piper's memory, and Gideon casts his own spell over Phoebe and Paige. This leaves Chris and Leo to both save them, and protect piper until Chris can be born.