“The Hive has placed a restraining spell on the bridge. A tomb husk will release it.”
When you make it outside head over to the left. Go to the first landing and then face the gap between the two sides of the area. You need to find a Tomb Husk that is down near the crossing point. The Tomb husk is ahead on the left, highlighted if you activate Ghost. Slip past the Swordbearer knight that patrols the area and get over to the Tomb Husk.