During an outbreak of the bubonic plague in the magnificent Seville of 1597, Mateo, a former soldier, returns, honouring his word to find and extract a dead friend’s son from the city. Previously, Mateo had been forced to flee the city to save his life, having been sentenced to death by the Inquisition for printing forbidden books. Before he can complete his task, Mateo is arrested by the Inquisitor’s bailiffs, who promise to pardon his life in exchange for solving a series of crimes of diabolic overtones being committed in Seville.