Does the question 'where the hell is entrance' sounds ridiculous? Actually it is not. Everybody should know where Icecrown Citadel is - if not, it's easy to see on the map. But entrance to new 5man instance set is cleverly placed on ridiculous place and hard to find. Well, here is easy� help - see the picture.
I was dumb enough to try and watch the scenes around Sword's Rest and, well, didn't get out of there quickly enough. In case you're wondering, Barkskin doesn't prevent your hearthstone from being interrupted. /sigh