Anyone who played the old Thief games might remember Garrett taking on a young apprentice. Apparently, Eidos Montreal doesn't want to have a young thief following him around, because during VGX they released a trailer for the new Thief, which shows her death. In the trailer Garrett is sad about her dying, and it looks like he will be motivated in the new game by revenge.
The trailer also has a bunch of creepy robed dudes who are trying to channel some primal nonsense in an evil ceremony, which will most likely lead to the destruction of the city. The story looks really bad to me, and I can't think of a trailer that could get me less excited about a game.