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.

When the Halliwell sisters are exposed as witches on nation-wide television, they form a pact with The Source to reverse time and undo the damage. However, in the process, one of the sisters makes the ultimate sacrifice, placing the Power of Three in mortal danger.

A warlock repeatedly attempts to kill the Charmed Ones, with a help from demon Tempus turning back time after each failure so that he can try again. However, because of the endless time loop and her power of premonition, Phoebe experiences a number of strong cases of déjà vu and is able to figure out that there are evil forces after them.

A powerful warlock shows up claiming that he made a pact with the sisters' mother in which he spared her life in exchange for the girls' powers. Fleeing him, the three sisters go back in time to the 1970s when their mother was still alive and they try to prevent the pact.

Phoebe accepts her new role in Cole's life, but she still sets out to save an innocent after she has a premonition and even seeks her sisters' help in protecting the man. Meanwhile, Piper's heart doesn't seem to be in it as she prepares to defend her family against any new threats from the underworld.

The Source breaks an age-old agreement between good and evil by stealing The Hollow, an ancient vapor which he uses to absorb Piper & Paige's powers. Meanwhile, Phoebe must allow Cole to help them, despite her having a premonition involving Cole sacrifici

In his twisted attempt to win Phoebe's heart back, Cole casts a spell that alters reality, that eliminates Paige as a Halliwell and destroys the Power of Three. Meanwhile, Paige suddenly finds that her sisters have no knowledge of her existence and that past villians have come back to haunt them.

When the sisters try to divert Zankou's attention from the Nexus, he hatches a plan to absorb all their powers. But when the girls realize what Zankou is up to, they are forced with a life-altering decision: sacrifice their powers or their lives.

When Phoebe has a vision of herself being burnt to death, the sisters travel ten years into the future to learn what happened. Only to discover that she used her powers to kill someone, causing a local DA to begin modern day witch trials as a platform for political office. Meanwhile, Prue and Piper try to save Phoebe, but they both are surprised and somewhat disappointed to learn how their lives turned out.

When the sisters discover that Cole is Belthazor, Phoebe must make one of the toughest decisions of her life: either vanquish her boyfriend or keep one of the most dangerous demons known to exist alive.

Mourning the death of Prue, Piper and Phoebe must now come to grips with the loss of their oldest sister, and the loss of the Power of Three. However, The Source discovers an unknown sister - the daughter of Patty and her whitelighter Sam, who had been kept hidden, Paige, the now-youngest Halliwell can restore the Power of Three and reunite the sisters' strength as witches.

Mourning the death of Prue, Piper and Phoebe must now come to grips with the loss of their oldest sister, and the loss of the Power of Three. However, The Source discovers an unknown sister - the daughter of Patty and her whitelighter Sam, who had been kept hidden, Paige, the now-youngest Halliwell can restore the Power of Three and reunite the sisters' strength as witches.

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.

Phoebe and Paige go to a summit meeting with the leaders of evil and discover that all magic - both good and bad - has disappeared enabling the leaders to steal Piper's about-to-be-born baby and welcome the twice-blessed child into the kingdom of evil.

Bianca, a woman from the future, arrives to take Chris's powers, and Leo learns that she is actually part of an assassin family of witches. Meanwhile, Paige decides to move in with Richard, while Phoebe ponders joining Jason in Hong Kong.

Gideon creates a portal that puts Chris and Leo in a mirrored world where evil prevails, and Phoebe and Paige travel to the parallel universe to rescue them. Meanwhile, Piper gives birth to baby Chris.

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.

Piper is attacked by demons and winds up in a coma, and as she hovers between life and death, her spirit meets a familiar face who wants to help restore Phoebe's faith in love. Phoebe, Drake & Paige rush to save Piper by attempting to locate Leo, who's memory has been wiped clean by the Elders in attempt to allow him to choose his own destiny: be an Elder forever or choose Piper, and become mortal.

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.

A warlock brings characters to life from old B-grade horror movies in an attempt to kill the Charmed Ones.

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.

In an attempt to destroy the Charmed Ones, Cole enlists the help of Andras, a demon who magnifies anger into rage. Meanwhile, when the sisters lose their magic after using their powers against each other, they are left defenseless against attacks from the Triad and Belthazor.

On the day of Piper's marriage to Leo, Prue's Astrally Projected-self adopts an uninhibited, wild personality that threatens to ruin the wedding and place Prue in jail for Murder.

A demon turns people into the embodiment of each of the deadly sins, including the Charmed Ones and Leo.

The Source sends Piper into a deep coma, where she perceives an alternate reality. Phoebe and Paige must find a way to return her to reality and save her from giving up her powers while she is delusional.