(Dis)appearing Guard
If Alrik the guard feels like he can trust the heroes with subtle detective work, he will approach them about a concern he has with one of his colleagues.
Larissa had disappeared for a couple of days some weeks ago and Alrik feels she has changed. And never provided a satisfying explanation for her disappearance.
The heroes are tasked to investigate Larissa. As she actually lives in the barracks (red O below) of the city guards, his main concern is what she does in her spare time outside the walls of the guards compound. She occasionally used to go out with some of her colleagues for a night out but after her return, she prefers walks alone.
As a guard she is quite attentive (Perception (12/15/15) 9, full stats on NPCWednesdays#29) and it might not be possible to follow her easily.
Eventually she will meet up with a romantic interest in the abandoned castle construction site (red X):
Here she meets Geppert and they appear madly in love.
With a description brought to Alrik he will conclude that this seems to be the reason for her change in behaviour.
What actually happened was that Gepper seduced her. She was then interrogated by the cult for a number of days and then Nameless Oblivion was cast on her and she is now a spy for the Cult in the City Guards and meets up with Geppert every couple of days to report and renew the Nameless Oblivion.