Where is the summon mistman tome in soul carin?

I believe I found inside a chest on a platform. It was behind some bars that you had to open by shooting one of the switches, there was a soul gem on top of this "Cage" area and also a women inside said cage.

Shooting with what? Arrows or magic?

Directions:
- Facing the entrance to the Boneyard, turn right
- Follow the wall around to the back
- From the steps you come upon, head due East toward the edge of the Cairn
- Climb up the steps you find there
- Take the tome...and one of Jiub's pages...and a coin purse
- Enjoy your new summons spell

Hope that helps

Either will open most bars, so long as you hit the blue glowing thing with something. But none of the new Spellbooks are found in the Soul Cairn in chests.