Online:Concealed Weapons

Quick Walkthrough
# Talk to Thane Fjora.
# Talk to Borodin and Golun Drenduf.
# Talk to Aera Earth-Turner, then investigate Betar-Nes' house.
# Return to the Thane's Hall.
# Use the glowing orb to talk to the projection.
# Enter the crypt through the secret passage.
# Kill the traitor and find Thane Fjora.
# Find Aera Earth-Turner and decide her fate.
# Return to Thane Fjora.

Detailed Walkthrough
Hauting says your news may distract the thane from a recent assassination attempt. Sergeant Aera Earth-Turner and her squad are looking into it. 

Enter the Thane's Hall and speak to Thane Fjora. You can also talk to Aera Earth-Turner if you want. 

The thane reveals that Betar-Nes was a Worm Cultist. Her advisor, Borodin, is questioning townsfolk at the inn, and her court mage, Golun Drenduf, is researching the Worm Cult. 

Talk to Borodin upstairs in the inn. He hasn't found anything, and he doesn't believe there is anything to investigate. He even thinks it's shameful that the thane had a fight with her housecarl, and suggests that Thane Fjora isn't fit to rule..

Golun is at the Mages Guild, directly across from the inn. He needs to check a book in the library, then he will meet you. Talk to Aera Earth-Turner while you wait. She wants you to check out Betar-Nes' house, south of the Thane's Hall. 

The Housecarl's House
Betar-Nes' house in the eastern corner is a Dark Contract. It says the spirits are key to unlocking Sinmur's power. Once you finish reading it, a Worm Cultist Assassin attacks you.

Head back toward the Thane's Hall with this information. Stop to talk to Aera on the way. She says Golun is dead, found in the library with a pair of smashed skeletons. She can't figure out how the cultists got past her guards, though.

A Murder in the Thane's Hall
Enter the Thane's Hall, go behind the stairs and examine Golun's body. It looks like he tried to hide a glowing orb behind his body. 

The Magicka Memory Matrix
When you use the orb, a glowing projection appears. It is a magic memory matrix; it holds all of Golun's memories. The last memory shows Golun realizing that the Worm Cult wants to use bound Companion spirits to make Sinmur stronger. The cultists are gathering in the crypt below Nimalten. Enter Nimalten Barrow through the secret passage in the fireplace. 

Betrayal
As you try to walk forward, Advisor Borodin appears. He is a Worm Cultist and wanted to get you out of the way. It's clear that he doesn't plan on fighting honorably, as he teleports you deeper into the crypt. A magical blue barrier blocks the door to his lair. You need to take the long way around to kill Anchorite Borodin.

Open the now unblocked door across from Borodin and head back into the Thane's Hall to check on the Thane. She says Aera was leading the cultists, but she was able to wound Aera.

Tracking the Assassin
Exit the Thane's Hall, and talk to the Nimalten Guard. He saw Aera head to the water. Go northeast, and find another guard who says she went into the crypt. Enter the crypt through the door near the water. On the wooden bridge, you find a half-burned note to Borodin. Use the trapdoor at the other end of the bridge to enter the lower level. There is another scrap of paper, this one by Littrek called Ode to Oinkers. 

Talk to Aera. The Worm Cultists convinced her that she would be able to see her dead family members if she gave them information. Then, the cult asked her to kill Golun and Thane Fjora for them. She is done with the cult. 

You can choose to kill Aera for betraying the Pact, arrest her, or tell her to run away and you will say she is dead. 

If you try to arrest her, she will reply that she can't face her family. She is going far away. You have to kill her if this happens. She runs into another section of the crypt. After she leaves, you can read ''Aera's Letter to Trynhild or Aera's Letter to Denskar'', depending on whom you chose to aid during the quest Crossroads in Bal Foyen. If you choose to choose to let her go, she will just run away towards the exit and you can proceed through the crypt to fight a Worm Cultist boss.

Return to the thane, who thanks you for your efforts.

Notes
If you go to the docks during the Bal Foyen questline, Aera will act as though her husband and son are dead, and her daughter is alive. However, if you go to the fort, the opposite happens; Aera's daughter dies, but her husband and son live.
 

Quest Stages