Turning to Stone is the fourth book in the Roma Underground series. We are in Naples and the story involves the Mafia. Enter a new member of the group, a young man, an intern who is very knowledgeable about the Mafia and come to find out that he knew Charlie Brooks, the young man who was killed in the previous book. Along with Bianca, Ferrugia, Dante, Gennaro, Allesandro and Silvio the story continues with Ferrugia going undercover as a member of the Camorra. The rest of the team investigates the death of a of a man, Aldo Giurlani killed in a car bomb that was thrown by people on motorcycles. A book is delivered to the team and it is up to them to figure out what this means. This book seems to be more indepth than the previous three or it is just that the plot is getting more intense. We also get another gastronomical treat with more food descriptions, more about Loki, Bianca's online friend. This part of the story kind of confuses me and I am anxious to find out who Loki is. This series is complicated but the author does a great job with the characters depictions and this tour of Italy is interesting indeed with each book getting more complex than the previous. I look forward to reading the last book in the series.