The secret of the monks

In a remote abbey on the edge of a small town, mysterious incidents have been occurring for weeks. In the study of a priest, four monks were recently found dead. All had black fingertips and black tips of their tongues. To rule out any devil's work, several suspicious brothers of the abbey were cruelly tortured and interrogated. A single woman from the nearby village was found guilty of witchcraft and burned. However, since all measures and investigations into this case have so far yielded no results, you have been secretly led into the old building by one of the brothers to find out who or what is behind the events. As all the monks disappear into the chapel for communal prayer, you enter the mysterious rooms in the highest tower of the abbey... Is the murderer hiding there?