After their fake funeral, hosted by father Victor, the sisters magically assume a permanent new appearance, hoping for normal, carefree lives, but the ploy also discontinues Phoebe and Piper's careers and relationships. Paige has neither, but her white lighter half can't be turned off, so she must respond to danger incurred by an overconfident witch, none other then Billie Jenkins. Agent Keyes suspects the sisters aren't dead and pretends to have abandoned their case, in fact leaving agent Murphy to observe the house discretely. Hell has been decapitated, but demon ...
When Piper goes for a job interview with a corporate recruiter, she's shocked to learn that the background check of her assumed identity was that of a woman wanted for murder. Meanwhile, Phoebe has a premonition of Dex being in an earthquake.
Wyatt's school play brings out the competitive nature in Piper when her hand-sewn costume and parenting abilities are criticized by another Stepford-like mother who is actually a demon in disguise bent on kidnapping Wyatt in a plot to resurrect the Source. Meanwhile, Paige spies Dex with another woman, and despite Phoebe's objections, butts in.
Billie is determined to kill a particular demon but can't when confronted by memories of when her sister was kidnapped on Halloween. A reporter is constantly harassing the sisters and Paige attempts to throw him off by impersonating the ghost of a girl he knew. Piper and Leo are having problems.
Agent Murphy calls upon the sisters to help captured a demon who has been infected with a government created virus that causes magical beings to turn "Incredible Hulk." They have to find an antidote to the virus after Billie catches it.
Piper is visited by the Angel of Death who warns her to prepare for the upcoming death of Leo. Piper who refuses to give him up, casts a spell that turns all males of San Francisco look exactly like Leo to confuse the Angel. He is still able to find Leo, however, when Leo makes a mistake by letting him know that he can see him. Leo gets run over by a car. Piper summons an Elder and Avatar for answers since "everything happens for a reason" and is led to an Angel of Destiny. She claims that Leo's death was a cause for their motivation to prevail in a future battle. ...
Phoebe thinks about moving on with her lives when she signs a lease for an apartment. Paige decides to tell Henry she's a witch, and so elicits magical help to put him in a good mood. Plans are put on hold when a demon shrinks them and traps them in a replica doll house of the Manor.
On the eve of the Chinese New Year, Piper and Billie receive a sign they think will help them return Leo. Instead, they find and disrupt a demon battle with the guardians of the Chinese zodiac, and Piper is charged with protecting their mystical staff. Meanwhile, Phoebe throws a house-warming party, and Paige introduces Henry to the world of magic.
Billie and the Charmed Ones deal with Christy's return, while a surprise suitor appears to ask for Paige's hand in marriage. Meanwhile, Piper runs into an old flame, and demons plot to recapture Christy.
Xar and his demonic challengers team play a dangerous game against the triad, trying to lure them to self-exposure against the charmed ones. Billie rightly suspects they are after her sister Christy. Piper hopes such high-level vanquishing may fulfill the prophecy terms to free Leo, in vain. Paige first delays her engagement party, then speeds up the wedding. Phoebe meets Cupid #3 'Coop'.
Students from Leo's magic school are being hunted by demons, and they arrive at the manor asking for help. Piper is confident she can handle the situation, but the demons are more powerful than she anticipated. Meanwhile, Billie takes Christy to see their parents, with tragic results.
After Cupido'Coop' pleads with Phoebe it's time to find love, a magical confrontation with her future daughters rekindles her child wish. Yet she still gives priority to helping Piper hopefully liberate Leo by taking on the ultimate power, which she rightly suspects, after conjuring an elder, to be Billy and her hostile twin sister, who are however part of an ancient trap they now risk closing. Paige concentrates on her charge Mikelle, a future white lighter, which black lighter Salek and his cahoot Dominique use as bait.
Dumain gets the hesitant Triad's okay to isolate the Charmed Ones by making them look unwilling to protect any of their magic friends. So he makes sure they get appeals but can't respond, being spell-bound by their private obsessions: a love-life with Coop for Phoebe, a home for Leo with Piper, a ring-conjured meditative isolation for Paige, so demons vanquish the messengers or worse. That allows Christy to win over Billie, who betrayed their secrets, completely and help send the trio to the underworld.
Dumaine and the Triad believe they can finally vanquish the Charmed Ones, now stuck in the underworld. Demon Nomed however successfully offers an alliance to overthrow the old demonic generation. Unwilling to accept defeat barring their return, the Triad has Christy and Billie conjure the Hollow, to Dumaine's horror. Coop declares his love but is bluntly told to wait by Phoebe and to but out by Victor. Cued by Leo's ghostly image, Piper decides the Charmed ones must do the same. A terrible battle occurs and wrecks the house, complicated by Dumaine and grandpa Victor ...