On the matter of the new prisoners: We have determined that they are indeed mortals from Nirn, Members of the Mages Guild, in fact. It was our excellent good fortune to capture these invaders.
It is clear that they have entered Coldharbour illegally and for purposes that are in direct conflict with the will of Molag Bal. We haven't had a trial in such a long time, and it should be a good show that helps bolster the morale of your servants. Of course, the verdict is a foregone conclusion.
As always, your justice is swift and cruel, my master!