Sean-H-

Firstly, you have to shoot out the straps from around her..using a sniper rifle..because if you use any other gun it is hard to see where they are and might kill her...then once you have done this, a mob of zealots should come and try and get her, you then have to kill them, once you have done that she will try and open a door, and it is locked so she needs to get the key, which the guy in the red suit has, which should come after she has tried to open the door..once you have killed him, and the rest of the zealots she will get the key from him, and then open the door..which then you have a sub mission with her..
Hope this helped