The Knife of Dunwall is the first piece of story-based DLC released for Dishonored. It’s a great slice of gameplay, built on one hell of a premise. Remember Daud, the leader of the assassins and all-round badass? I’m sure you know the guy… hung out with those BAMF-ing dudes with the gas masks… straight up murdered the Empress at the start of the story… was either killed or spared by you near the end?
You with me? Cool. He was a somewhat conflicted character in Dishonored: a hardened mercenary and killer, he was nonetheless guilt-ridden over his role in the death of the Empress and the city’s descent into chaos. The Knife of Dunwall tells Daud’s story, following him from that fateful day at Dunwall Tower through to – presumably – his confrontation with Corvo.
From: http://www.ign.com/articles/2013/04/18/dishonored-the-knife-of-dunwall-dlc-review