Speak with Mayara Brightwing in the Burning Steppes.
An agent of mine, Mayara Brightwing, was sent to the Burning Steppes to scout the ruined city of Thaurissan. That destroyed city of the Dark Iron dwarves may hide objects of great value... objects that would fit nicely into our family museum.
Mayara says she found something and will need aid in retrieving it, but it is not in Thaurissan. Instead, a foray into Blackrock Spire will be required.
I do not know the details, but if interested then speak with Mayara in the Burning Steppes.