Vhezyen raises an eyebrow, then nods, taking Mordred's implied meaning. The point here was to play along, as if unwanted ears were listening in on their conversation. Vhezyen spoke even softer, to show respect for Mordred's concern, although the group had already been speaking in hushed tones. "I see. However, we have the privacy of this room. Beyond this, only powerful magic could be used to spy on us." He glanced around the room, addressing all. "If that's the case, then our efforts to be clandestine are in vain. Such magic would allow them not only to hear us, but to see as well, from any distance on this plane of existence."
With that, Vhezyen picks up the knotted string, thoughtful. "If we are being spied upon in this manner, there may be something we can do to avoid passing knowledge to our enemies." Turning it over in his hands, he thoroughly examines the knotted string, paying close attention for any clues it might hold.
Even though Vhezyen doubts the group is being watched, he's new to the situation so respects the possibility. As such, he attempts to discern the meaning of the knotted string to the best of his ability. I'll use my last Portent roll of 18, along with whatever is appropriate: Arcana, History, Investigation (all +10), coming out to a 28. Also, whatever info Vhezyen gets he can put on paper using the 'Illusory Script' ritual, making sure only those present can read the words, no matter who is watching.
I had the above typed up before I saw Octo's post about Domarc's recognition, so might as well drop it in, as it might support or elaborate on what Domarc discerns. I was wondering when we'd get to this (I didn't know Domarc was Mezian until he dropped the clue during breakfast!).