This new book by Salvatore Lupo is a translation from the Italian. I read a bunch of Mafia books before leaving for Sicily and this one has, by a considerable margin, more economic history and more analytic reasoning than the others. It asks how the Mafia interacted with more general changes to the Sicilian economy and also asks why the Mafia were stronger in some parts of Sicily than others. The latter sort of question is a no-brainer for an economist but it doesn't pop up very often in the literature.
On the American Mafia, Mike Dash's The First Family: Terror, Extortion, Revenge, Murder, and the Birth of the American Mafia is both good and readable. See for instance the Jonathan Yardley review at the Amazon link.
The Mafia is a topic I will never understand very well, so it is hard for me to judge the substance of these books but they do signal various impressive qualities.