After Melchior narrowly escapes an attack, he realises that someone is trying to mislead him. He has to hurry, because more and more people's lives are in danger. The pharmacist has growing doubts about his new apprentice.

Melchior receives a crucial clue from an old monk. The key to the ominous murders seems to lie in a tragedy involving betrayal, heartbreak and revenge. Keterlyn's secret also comes to light.