The Roman Sacristan tells us about a plenary indulgence for Christ the King, which is tomorrow (Sunday). Sorry I did not spot this sooner.
Visit the Roman Sacristan to get the details.
More on Christ the King:
Fr. L W Gonzalez on the history
EWTN: Litany to Christ the King
Pope Pius XI on December 11, 1925: Quas Primas (on the Feast of Christ the King)