Sweetie Belle is the last Crusader without a mark. Feeling abandoned and lonely, she asks the Doctor to take her to the Crystal Empire, where her parents are vacationing. However, a glitch in the TARDIS means they arrive a little early; specifically, right at the end of Sombra’s reign. However, there may be more to this empire than meets the eye. The king is a puppet, and the walls themselves are full of negative energy. The travelers find themselves in a fight for their very minds against the empire itself.