Charmed begins when the three Halliwell sisters come together sometime after the death of their grandmother, Penny. Upon moving into the old family manor in San Francisco, the youngest sister, Phoebe, discovers an old book in the attic. Reading an incantation from the Book of Shadows, she sets in motion events that fulfill an ancient prophecy.
The sisters discover that they actually are descended from a long line of witches. The first witch in the line, Melinda Warren, prophesied that from her line would come the Charmed Ones. A force of good, they would be three sisters gifted with powers to battle the forces of evil. Prue Halliwell, the oldest sister, has the power of telekinesis and astral projection. Piper, the second-oldest, has the power to change the speed of molecules in objects and people, either slowing them down to the point where they are frozen in time or accelerating them, which effectively causes explosions. Phoebe, the third sister, has premonitions and the power to levitate; in addition, she is an empath (supernatural ability to read others' emotions).
After Prue is killed, it is revealed that there is a fourth sister, Paige Matthews, their mother's illegitimate child. She has the power to "orb" in and out from place to place like teleportation, to orb objects to herself or another place, and the power to glamour, which allows her to change her appearance. She has the same mother, Patty Halliwell, as the other three, but her father was their mom's whitelighter Sam. Patty and her Whitelighter lover gave Paige up for adoption, with the sole condition being that the adoptive parents give her a first name beginning with "P".
A central theme throughout the show's run is the sisters' struggle to balance normal lives with their supernatural responsibilites. The burdens of keeping their Charmed destinies a secret from the outside world has repeatedly created tensions in their friendships, workplaces, and romantic relationships. Only a few know their secret and help them on a regular basis. The most important is Leo Wyatt, a Whitelight assigned by the Elders to guide and protect the sisters. Leo means a great deal to the sisters both professionally and personally: he heals their wounds, advises them collectively and individually, and mediates between them and the enigmatic Elders. He also happens to be the love of Piper's life; their romance is an ongoing plot thread that dates back to the first season. A few of the others who haved kept the Charmed Ones' secret over the years (and appeared in the opening credits) are Police Inspectors Andy Trudeau and Darryl Morris, tormented half-demon Cole Turner (a.k.a. Belthazor), and mysterious time-traveler Chris Perry.
