So at level 100, I could not often get missions that advanced the plot for this event. I only got as far as "kill the Elites".
I'm curious, how many stages were there for this event? Sounds like there was some boss fight at the end? I couldn't find any information about that this event anywhere other than "this event has started and will finish at this date".
Oh, and my pursuit of Unsavory Business resulted mostly in the demise of thousands of Dark Eldar, nevermind that I was seeking a different type of foe this last month.