The Secret of the Dead Monks

Italy in the middle ages. In an abby, 4 monks are found dead - all of them have black spots on their fingertips and on their tongues. But nobody is investigating the case: innocent women are burnt as witches and the next best monks are tortured cruelly. But you find that story suspicious, so you are beginning to investigate this case in secret. All signs lead to a library in the highest spire of the abbey. You wait until the weird librarian is gone and step into those mysterious rooms... Is the murderer hiding inside?