The Song of Pelinal
When Al-Esh is asked about the topic "Investigate" after finishing The Spirit Barrier, this quest starts.
"Queen Alessia has requested that I find a means of passing through the Spirit Barrier to find and/or rescue Pelinal Whitestrake. Perhaps I should find out more about the nature of the barrier."
Pelinal has gone off to attack Umaril the Unfeathered by himself. Asking about the "Spirit Barrier" that surrounds White Gold Tower will give a further update.
"The Spirit Barrier appears to be planar nexus to Meridia's realm. Perhaps passing through it is similar to the ability to travel to Meridia's realm."
Leave Al-Esh's throne room. As you leave, Naomi approaches you yet again. Although there are two conversation topics, it does not make a difference which one you pick. Then ask her about the "Spirit Barrier" and she will tell you more.
There are dead Ayleid Soldiers and Aurorans scattered around the outside of the tower - if you visited earlier they were still alive. Enter the tower and in the room ahead are four Ayleid Sorcerers standing around an object on the floor. Kill them and then look at the object, which turns out to be Pelinal's head.
"Pelinal has been dismembered, yet his decapitated head is still alive - barely. He says that he was paralysed by an Ayleid wearing futuristic armour - it must have been Gareth! Pelinal also told me that his heart is his conduit to the gods. He instructed me to take it from his chest cavity which Umaril took upstairs."
"On touching Pelinal's Heart, a surge of power coursed through the Crusader's Relics as if responding to their master's call, radiating their newfound powers. The red diamond is continuously energising my body while sending me what must be whispers from the Eight Divines."
The heart has some nice properties. Go back down and you will see that Alessian troops have occupied the tower. Morihaus and Pelinal's head are talking, so go and speak to Al-Esh. This ends this quest.
You had promised to find Gareth for Pelinal. When asked, Al-Esh suggests that any prisoners would have been taken to Fanacasecul, so return there.
When you enter, you find a number of dead Alessian Soldiers.
"The soldiers guarding Fanacasecul are all dead! I'd better check if Naomi is alright."
Fanacasecul is almost deserted, but there is one Alessian Soldier outside the throne room. When you speak to him, your log updates.
"Gareth is here at Fanacasecul! He has opened a time portal inside Queen Alessia's throne room and Naomi is inside facing him alone. I must find a way to get inside!"
Now go to the Visitor's Tent and read Naomi's Journal.
"Naomi's journal suggests that Gareth might be trying to make a false Amulet of Kings. If he succeeds, he could relight the Dragonfires and be crowned Emperor of Tamriel! I must find a way to stop him."
When you leave the tent again, the soldier runs over to you and asks you to report the attack to Morihaus and Al-Esh. Return to White Gold Tower and speak to Al-Esh
When the subject "Petrify" arises, she tells you that they can turn you into a statue for 4,000 years, and any possessions of yours that you place in the chest in the Visitor's Tent will also be preserved
This completes this quest. Make your way to the main room of the Shrine of the Crusader. There is an unfamiliar Knight of the Nine there, an Argonian named Dreekius. He may be camping or, as is more likely, fighting undead as there has been more than enough time for them to respawn. Fortunately, he can't die.
Speak to Dreekius to get information on what has happened in your absence - it seems you have been gone a year and Gareth has made himself Emperor, and the Knights of the Nine are now outlaws, and the series continues with Revelation.