When the Great and Powerful Trixie seems to be at the end of her life's journey, she is unwilling to let go. An unusual shadow on a cave wall has a bargain for her. He will teach her powerful magic that no other would dare teach to her. In exchange, she must follow directions.

Princess Celestia arms Twilight Sparkle with a new spell to confront the new menace, but it is not enough. The unicorn must look past her mistakes to face the one unicorn in all of Equestria that she fears most. Will the steep price of redemption be worth paying?