Husam is a drunk thief and an ex-employee of the Iron Throne who will reveal the names of their leaders, as well as the fact that they are planning an operation in Candlekeep. When you return to Baldur's Gate in Chapter 7, he will ask you to meet him outside the Blushing Mermaid. If you speak to him there, he will reveal himself to be a member of the Shadow Thieves sent to investigate the source of the rumours being spread about Amnish involvement in the recent troubles. If you agree to work with him, he will ask you to deal with Slythe and Krystin.