Thieves Guild has been playing Mask of the Betrayer so fast that it already has a part of the walkthrough ready and waiting for you. Sad is the life of a newsman, having the game spoilt before finding time to play it, but I'll go no further than this little excerpt for those of us who don't want the game spoilt either. So here it goes:
You'll awaken in a large chamber on a stone floor. The spirit forces are keeping you pinned down. As you look around, you see drawings on the walls depicting spirits acting out ancient rituals. Moments later there is a puff of smoke and you see a woman in red robes approaching you. It is Safiya, and if your lore is high, you'll recognize her a Red Witch of Thay. She dispels the spirit forces holding you and you rise. You will converse with Safiya for a bit, and then she will tell you that you need to leave as quickly as possible. In this initial dialog there is already a chance to gain or lose influence with her, so be careful with your responses. Gains and losses will appear on the screen.
For more spoiling refer to Thieves Guild
. While that's a walkthrough and not a review, the current character of it - an Act I walkthrough - enables it to serve as, essentially, an extended close-up, detailing the storyline and such, rather than camera angles and the quality of effects. Be warned of heavy spoilers, though, once again.