Emerging from the mansion's plumbing system, the legendary Lady of the Lake (Danielle Bisutti) solicits the aid of the Charmed Ones to protect the enchanted sword Excalibur. As a result, innumerable strange characters -- possessing powers ranging from evil to really evil -- show up at mansion, hoping to pull the fabled sword from the fabled stone. As it turns out, the only one capable of pulling it off (or should that be "pulling it out"?) is Piper (Holly Marie Combs), who now must locate Excalibur's rightful owner before the sword's power overwhelms and destroys her.
by Hal Erickson synopsis