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.

When Phoebe feels the pain of an injured American-Indian ghost she sees in a deserted town, Prue travels back in time to the mid-1800s to save the man, and Phoebe, from death at the hands of a local thug.

Phoebe has a premonition of a murderous banshee while adding on to the Belthazar section of the Book of Shadows, thus causing her to think Cole is responsible. But when the sisters cast a spell it backfires and turns Prue into a dog, and when Prue gets hit by a car, Phoebe's remorse causes the banshee to attack her, turning her into a banshee.

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.

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

Phoebe tells Piper and Paige that she is pregnant, and that Cole is the father. Meanwhile, Piper and Paige team up with a wizard to stop the coronation of the new Source, unaware that it is Cole and Phoebe is soon to be his Queen of the Underworld.

Piper, Paige and Leo struggle to convince Phoebe, now a mermaid, to come back to her life as a Charmed One, when she decides to ""swim"" away from her problems with Cole. Meanwhile, Piper casts a spell to stop her panic attacks but instead of facing her fear, she suppresses it, endangering herself and her baby, when a sea Demon comes after her mermaid sister, Phoebe. In order to help Phoebe, Paige takes drastic measures and enlists the aid of Cole, and his newfound demonic powers.

Paige gets to know the Whitelighter in her, when she meets her first charge, a man named Sam, unbeknownst to her is actually her real father. Meanwhile Cole tries every possible way to get himself vanquished by the Charmed Ones. Piper and Leo have problems in finding a magical creature that does the babysitting part, and things go bad to worse when they're poisoned by a Darklighter, leaving Sam as the only one who can save them.

A demon attacks The Charmed Ones with dream dust, causing their nightmares to come to life. Paige is harassed by an evil clown at a baby shower, Piper has an affair and Phoebe is chased by a maniac with a chainsaw. The sisters must use magic to put themselves to sleep to re-enter their nightmares and unmask the symbolic meaning of their dreams.

When Grams comes to the manor for a Wiccan birthing ceremony, for Wyatt, the sisters find out that she has brought a memory from her past, a former lover who wants to kill the Charmed Ones and bring back the love they once shared. Meanwhile, Phoebe contemplates Jason's invitation, even though it will take her away from her family, and Paige casts a truth spell to figure out if Nate can accept her being a witch.