What is Dishonored: Death of the Outsider?

Bethesda Softworks and Arkane Studios want us to "pull off the greatest assassination ever conceived" in Dishonored: Death of the Outsider when it launches on September 15th, but before we take on such lofty goals, they first want to set the stage of what this latest entry to the series is all about. Roll a two-minute video of creative director Harvey Smith talking all about the next game: