The fairy tale is actually a memory of Paige’s past life as the Evil Enchantress . Her past self follows the prince to the present day to reclaim him and secure her dark legacy.
Paige accidentally conjures a medieval prince into the 21st century after casting a spell based on what she thought was a childhood fairy tale.
The episode features the primary series regulars and several notable guest stars: Charmed Episode Re-Watch - S4E6 - A Knight To Remember
If you are looking for information on Season 4, Episode 6, titled "A Knight to Remember," Episode Summary: " A Knight to Remember "
Originally aired on 1 November 2001, this episode focuses on Paige Matthews discovering a dark secret about her history.