Tenyeminwe, involved in the vanilla quest https://en.uesp.net/wiki/Morrowind:Escort_Tenyeminwe, leaves to Summerset Isle at the end of the quest. Pralec suggested she might have connections to the Firewatch MG chapter, as a means of pointing players to the mainland during the MG questline. The backstory is that Tenyeminwe was collaborating with Banvira and whatever research they were doing is the reason the Telvanni are after her.
The quest can be started anytime after completing the first stage of the Hlaalu stronghold. A messenger appears at Rethan Manor carrying a letter from Tholer Andas in which the player is invited to Andothren and pointed towards Dreynos Helvi for work. Talking to Helvi finishes the quest.
