Online:The Bleeding Temple

Quick Walkthrough
# Talk to the Drake of Blades at the Alliance Rally Point in the Temple District.
# Free the clergy members at the Shrines of Mara, Dibella, and Julianos.
# Talk to the Drake of Blades in the Temple Rectory.
# Rescue Father Egnatius from the Temple of the One.
# Talk to Egnatius in the Temple Hideout.
# Report to the Drake of Blades in the Alliance Base.

Detailed Walkthrough
The Drake of Blades is looking for someone. The Daedra kidnapped a priest named Father Egnatius, whom the Drake had contact with. Unfortunately, he must be very valuable to Molag Bal, as the priest is never kept in one place for very long. The Daedra have been torturing the city's clergy near the shrines to the Eight. The Drake suggests splitting up and freeing the priest, hoping that Egnatius will be among them. The Drake tells you to meet her in the Temple Rectory when you're finished.

You need to free three members of the clergy. You'll find a Priest of Julianos at the Shrine of Julianos, located in a ruined building by the northeastern wall. A Priest of Mara is being tormented at the Shrine of Mara, opposite the Shrine of Julianos; the Shrine of Mara is located by the northwestern wall. The last clergy member, a Priestess of Dibella, is located at the Shrine of Dibella. The Shrine of Dibella is inside a building in the southwest corner of the city. When you rescue your third priest, they'll tell you the Daedra have taken Father Egnatius to the Temple of the One, which lies in the center of the district.

You should find the Drake and tell her what you've learned. The Temple Rectory is in the southeastern corner of the district, east of the Monstrous Tooth Trophy Vault. You'll find the Drake at the bottom of a flight of stairs. She informs you that Father Egnatius being held in the Temple of the One is bad news, as there are a lot of Daedra guarding the Temple. People don't survive very long in there, and you need to act fast. 

Exit the rectory and start heading for the Temple. You can enter the Temple of the One from the south, the east and the west. Egnatius is being interrogated by a Xivkyn named Xotos Vel. She's using Imperial Citizens as leverage, killing them in an attempt to get Egnatius to talk. When you engage her in combat, she will be joined by her two assistants, as well as another Dremora and a Grievous Twilight. Six more Daedra will appear in the Temple as her and her minions are defeated. Once all of these Daedra are defeated, you'll hear a roar from above. A Daedric Titan named Uzurus will crash through the ceiling.

Uzuruz is considerably harder to defeat than Xotos Vel. He has two abilities in particular that you need to watch out for. First off, when he rears up on his hind legs and brings his forelegs down with force, that indicates he's going to breathe fire and leave a trail on the ground, which deals a lot of flame damage when you stand in it. The second thing you need to look out for is when he jumps. The shockwave deals an insane amount of damage. You need to either block or get out of range in order to avoid taking too much damage. Put up damage shields, heal when necessary, make use of roll dodges and try your hardest to survive. Once Uzuruz is defeated, a chest with your reward in it spawns in front of Father Egnatius as he is released from his bonds, and you'll hear a commotion outside.
:Dremora Caitiff: "To arms, kyn! That accursed Drake is setting off kindlepitch barrels again!"

The Drake is distracting the Dremora outside. Egnatius takes this opportunity to flee the Temple of the One. He tells you to meet him in the southwest corner of the district before he leaves. Go ahead and find this meeting place Father Egnatius awaits you in. It's called the Temple Hideout, and you will enter through a well. Speak with Father Egnatius.
:''"You escaped! Thank the Eight. The Daedra know about this place. We shouldn't linger."
:Are you all right?
:"Yes … yes, I'm all right. Just need to catch my breath. You have my deepest, deepest thanks. I only wish more could have been saved."
:The Drake of Blades told me that you might know something of Molag Bal's plans.
:"The Drake sent you? Mara bless her. In truth, I don't know much. Molag Bal's inquisitor, Xotos Vel, was asking all kinds of questions about a scroll we recently discovered. I told her I didn't know anything. She wasn't convinced. Eight forgive me."
:So you do know something about the scroll she was asking about?
:"Yes. And no. I found it tucked between some of Marukh's polemics, just before the invasion. I've spent the better part of thirty years in those archives, friend. To find this scroll just days before the anchors fell … it can't be coincidence."
:What's written on the scroll?
:"Arcane references, ancient symbols …. It's not an Elder Scroll, mind you. It's nothing so majestic. But there is power in the text, of that I am certain. Alas, I had to part with it. But don't worry—it is in good hands."
:Do you think you could read it if you saw it again?
:"Given time, yes. At the risk of sounding vain, I doubt there are any other priests in the city who can unlock its power. It's in the gaps, you see? The syntax. The text beneath the text. The Eight guided me to this scroll. I must find out why."
:Fair enough. Get to safety. We'll see about getting you this scroll.'''

The Daedra were interrogating him because they wanted to know about a scroll he found before the Dark Anchors fell. After you finish speaking to Father Egnatius, you need to find the Drake of Blades in your Alliance base to be rewarded for your daring rescue.
 

Quest Stages