The Secret of the Dead Monks

Four monks are found dead in an abbey. They all have black spots on their fingertips and on their tongues. However, no investigations are carried out in this mysterious case. Instead, innocent women are burned as witches and the next best monks are brutally tortured. You are not willing to accept this. The story seems highly suspicious to you. You start to investigate secretly. The clues lead to the library in the highest tower of the abbey. You wait for a favorable moment. When the old, strange librarian has to go to a one-hour meeting, you see the opportunity you have been waiting for! You enter the mysterious rooms ... Who is the murderer and could he possibly be hiding in the library?