This quest can be started in a few ways. One way to start it is by killing Ambrus during "The Gilded Gauntlet" quest and reading the Note for Ambrus found on his body after the fight.
Something unusual happened in Svartrau. It might be worth checking out - any trouble in the city could spell trouble for Brencis.

1. Investigate the rogue vrakhir presence in Svartrau
I should head to the city and look around for anything that could lead me to the vrakhir.
1.1. Investigate the area by the north-east wall of Svartrau using Focus Mode
I should look around near the north-east wall of the city for anything that could lead me to the vrakhir.

1.2. Investigate the alley using Focus Mode
Something happened in the alley by the north-east wall of Svartrau. Looks like signs of struggle - might be worth taking a closer look.


1.3. See where the damage leads using Focus Mode
Whoever was fighting in the alley, it looks like they took it somewhere else. I should look around.

1.4. Use vrakhiri skills to investigate the roof
The alley fighters might've damaged the nearby roof - a vrakhir could've been involved. I have to use my vrakhiri abilities to scale the building.

1.5. Use vrakhiri skills to follow the rooftop tracks
It wasn't just one roof that suffered - I see others ahead have been damaged. Should be easy enough to follow and see where the vrakhir went - and why the roofs suffered for it.

1.6. Investigate tracks on ground level
Investigate tracks on ground level.

1.7. Get inside the building
The vrakhir might be inside the building. Let's see.

1.8. Defend yourself
The rumours were true. The rogue vrakhir is here and she's out to get me!


1.9. Interrogate Nish
Lacra believes the uriashi might have important information about Brencis's sire, but to get it, we need to access their village. Nish can tell us how - I have to figure out a way to make him talk.

You have my word. > I promise. > You're not killing him.
1.10. (Optional) Find a way to learn the location of the uriash village
The interrogation didn't go as planned - Nish is dead and we still don't know where the uriashi live. I have to find out from another source.
1.10.1. (Optional) Speak to Nish's corpse using Compel Soul
The uriash who knew the location of their village is dead. If we want to learn about Brencis's sire's whereabouts, I might need to speak to his corpse.


1.10.2. (Optional) Find a source of information about the uriash village
The uriash Lacra had captured is dead, but he wasn't the only person who knew where their village is. I'm sure I can find out the location from elsewhere and we can figure out where Brencis's sire is.
2. Endings
...
We know our next step - we have to climb the mountain following the windchimes to reach the village and ask about Brencis's sire.
...
Associating with the rogue vrakhir didn't seem like the right thing to do. Too unpredictable - I can't risk it.