Run/jump across the first lot of collapsing bridges into the first alcove, then go up the stairs. From there you'll need to make your way along the ledges to your left. You'll have to take cover in the alcoves along the way while your stamina regenerates, keep back as far as you can to avoid its bites and dodge about when it tries to breathe poison at you.
Eventually you'll reach what seems to be a dead end with a sheer drop in front of you. If you look up to your left there's a broken beam over hanging a hole high up in the wall. Use a rope arrow to get up there and escape.
This video explains it better.
Originally Posted by gamer
