Scholarium - Tapa dura

Frederico Casall certainly wasn't beloved; not by his students or his wife. But who would have hated him so much as to kill him? That is the mystery that Konrad Steiner, a Master in the Arts faculty of a Scholarium in Cologne, Germany, must solve.
Discovering the identity of the murderer is a task made more complex by the fact that the murderer is leaving riddles for him to solve. Will the puzzles lead Steiner to the solution, or is the murderer mocking his ignorance? Could the murderer be a member of the faculty, and opponent of the philosophical tendency represented by Casall? Or is there any basis for the rumor that Casall's young and well-read wife, Sophie, might have had good reason to rid herself of him? Steiner finds himself confronted with a riddle that is more than philosophical when Sophie vanishes without a trace.