The Ivanov Diamond by Charlotte E. English

Konrad Savast is the Malykant: foremost and most secret servant of the God of Death. His job? To track down the foulest of murderers and bring them to The Malykt's Justice. No mercy. No quarter.

Konrad is called to the death scene of a simple baker, and he can’t understand why. According to appearances, Pietr Orlov’s death was a natural one. Except there’s one problem: there’s no sign of his ghost. When two more bodies turn up with missing souls, Konrad knows he’s got a strange case on his hands.

But what could possibly connect the deaths of a baker, a manservant and a rich merchant’s wife? With the city police busy with the theft of a great diamond, Konrad must rely on the help of his one true friend to solve the case.

But when he begins to see links between the three murders and the theft of the diamond, he realises this case is more serious than he thought. With time running out, he must find the perpetrator and exact his vengeance - before a still worse crime is committed.