*** SPOILERS ***
I am hoping to run this adventure soon for a group that is new to AA (as am I). I think I have reasoned through most of the adventure. But, there is one part that isn't clear to me. Why are the PCs attacked by Thule cultists when they visit Marie? Is that not of Amanda's doing? Is it simply coincidence that they are attacked by Thule after Amanda sends them to talk to Marie? It doesn't make sense that she would hire them to find Martin, only to have them attacked shortly there after.
Overall, my thinking is that Amanda was using Martin to find this artifact. But, she didn't anticipate intervention from Adb Al-Hazred and actually lost track of him. She hires the PCs to find him and tails them to the ME. However, this still leaves the attack by Thule in NO unexplained... unless, as I mentioned, it was simply an uncoordinated coincidence.