The Realm Of Trapped Souls
Irene and Serana learned by the Elder Scroll after the Moth Priest had read it that it was two other Scrolls required to find Auriel's Bow.. Dragon Elder Scroll - which Irene already had for some reason, and Blood Elder Scroll.. Serana knew, or maybe hoped her Mother had to find out where she was.
Bringing the Moth Priest safely back to Fort Dawnguard, where he read up the Scroll Serana has been carrying around for so long.
Footless in the dungeon - poor guy..
And the trust against eachother grows:
Irene: "C'mon.. pull the chain.. whats the worst that could happen?!"
Serana: "Well.. considering its a Gargoyle statue standing right by the chain.. doesnt it look suspicious to you?"
Now where is your body, Wolf?
The portal to Soul Cairn..
Serana does not like this place one bit...
Hole in the sky.
Souls floating around like orbs.
Meeting Valerica, Serana's mother.
Angry undead's Frostbite against Flames.
After the trip in Soul Cairn, the Moth Priest was unable to read the Blood Scroll so he had to hope Irene would be able to gather the "Moths" to make her able to read it instead...