After a ballerina is found dead from dancing herself to death, Sam (Jared Padalecki) and Dean (Jensen Ackles) look into the case and discover the ballet slippers she wore were cursed. When Dean accidentally touches the shoes the power of the curse starts to take hold of him.
I see a familiar face from the preview below. It seems "Castiel is back!" Is he really back or just a fragment of Sam/Dean's memory?