"The third dose of Stiffeniis (Days of Atonement, 2008, etc.) boasts the same strong evocation of history and, refreshingly, a looser and more confident narrative voice."
"The superb whodunit ... subtly probes the heart of human darkness. While some readers may anticipate the solution, the pitch-perfect evocation of the period and the compelling, gloomy atmosphere more than compensates for any lack of surprise."
--Publishers Weekly (starred review)
"Philosophy and chemistry run amok in this intelligent [and] compelling...thriller."
"[Gregorio] excels in his depiction of an unusual sleuth who combines the wily psychology of a conquered people with the underlying philosophy of his former teacher, Emmanual Kant. Recommended for mystery readers who like literary historicals."
"A Visible Darkness is one of those books that any true fan of historical crime fiction will love. Characters are fascinating, the setting superb and the deduction is highly intelligent, and it's done perfectly true to the history. Best of all, this is the third book in the series...[Hanno Stiffeniis] deals with moral and personal dilemmas in this intelligent, skillfully-plotted and elegantly written book."--The Globe and Mail