A Vampire queen orders an attack on Paige with the hope of turning her into a vampire. With Paige on her side she hopes to turn Piper and Phoebe, and with the charmed Ones on her side, she then hopes to prevent the coronation of a new Source.
It's about Piper from the us-series charmed in the episode 3x22 where she dies and 4x01 where she tries to return Prue. It's called Piper, stay strong ...