Yes, there was definitely something unusual going on! Hmm... how can I find out what it is? I decided to simply follow them...
The procession headed straight to the chambers of the Supreme Lich (as I learned from the Vampire's confused thoughts). Unnoticed, I followed them...

Having driven away the clumsy skeletons and sent the vampire "far away," the Lich closed all the doors tightly and headed to the chest... Oh, there's a reason for that! The chest turned out to be completely filled with ancient scrolls - apparently, these worms had dug up some ancient repository... He reviewed them all, rubbing his hands with satisfaction.
After some time, the Lich left, locking the door and giving orders to the skeletons standing at the door to guard it carefully.
I approached the chest, trying not to make noise... Urgash, there's some kind of spell here - the lid wouldn't open!!!!