I have got to the place where I got stuck, years ago, and gave up. This is supposed to be the hardest part of any Tomb Raider game, at least so far...
This clip shows the level, but the player is using debug mode, which means they have all the weapons and an upgrade in running speed.
The problem you have to solve in this level is to shoot the ghost enough times that it pauses for a few seconds. Then you have to run and pick up the glowing book from the statue. If the ghost wakes up, the book moves to a different statue. every time the ghost touches Lara, she loses health and quickly dies.