The expansion also comes with an “Original Game Plus” mode, which lets you play through the Death Of The Outsider story with “a selection” of the abilities Emily and Corvo can use in Dishonored 2.
It’s a standalone expansion about trying to assassinate The Outsider, the magical goth who gifts powers to the protagonists in Dishonored games and prattles in an irritating way.
I haven’t yet got round to playing Dishonored 2 despite loving the first, so it seems awfully rude of Bethesda and Arkane to announce Dishonored: Death of the Outsider [official site].
Death of the Outsider is due for release on September 15th.