Three months the death of their mother, Charmed catches up with sisters Maggie and Mel, who are dealing with the loss of their parent in vastly different ways. Maggie is pledging the sorority Kappa Tao Kappa, while Mel focuses all her built up anger against taking down the patriarchy, especially Professor Thane, the teacher who has recently been released of sexual harassment charges.
As the sisters butt heads over their contrasting lives, new to town Macy shows up at their doorstep, announcing that she believes she may be their half sister. Mel originally rejects the idea, claiming it too much of a coincidence and sending Macy away, but soon the all three girls start experiencing strange occurances. Mel seems to freeze time while chatting with her ex over coffee, Macy moves a beer bottle (across an entire bar) when she gets upset, and every time Maggie touches someone, she can read their mind.
After experiencing these peculair phenomenons, the girls collectively wake up, tied up, by the Universities new womens studies teacher. He announes himself as Harry, their white lighter and healer, then relevealing to them that they are in fact the Charmed ones, the power of three, the most powerful withces in the world, who are destined to save the world and battle evil. He tells him they have 24 hours to accept their fate as witches, or their powers (and their memories of the supernatural) will be reversed forever.
After the reveal, Maggie runs into a possessed dog, and Harry alerts the girls that demon world must have gotten notice the Charmed ones powers have awakened. On the hunt to disover the demon who killed their mother, they suspect Lucy, the head Kappa Tao Kappa sister, but quickly figure out their mistake. Their next guess is Maggie's slightly over possessive ex boyfriend Brian. Maggie reads his mind and realizes he is in fact possessed, and the girls perofrm an exorcism on him, assuming htey have found, and vanquirshed, the evil that has killed their mother.
Later the girls realize that the demon who killed their mother created a chill in the air, therefore that Brian couldn't be the culprit. Figuring out that the true villian is misogynistic Professor Thane, the girls rush to the University to vaniquish him. While there, Harry appears and tells them they have to accept their fate as the Charmed ones in order to defeat Thane.
Realizing that this is what their mother wanted for them, they agree to the power of three and defeat Thane. Yet before he dies, he reveals that he isn't the one who killed their mother, and it's only now "just begun."
The episode concludes with Macy moving into the house with Mel and Maggie, wondering if they could find a way to contact her.
Before the credits roll, the girls take out a ouija board and recieve an urgent message from their mother:
Do Not Trust Harry.