How to get to Dasha Vestibule?

I went throught the story first picking up Master of Whispers to get to Vabbi instead of picking up Margrid the Sly. When I finished the story and defeated Abaddon, I came back and picked up Margrid and did the Poghan Passage mission. Now how the heck do I get to Dasha Vestibule to do this mission? There's no NPC offering me primary quests at the Grand Court or anywhere that I can find to get me there.

Anyone know?

Head out the NW exit from from Honur Hill and keep heading NW - a few yards right of the res shrine something should happen

Hm... A random, unmarked spot in an explorable area. That would have taken ages to find on my own.

Thank you.