Grade: B+

Roberto Saviano’s book dissecting the business of crime in Naples, a sensation in Italy that forced the author to go into hiding to protect him against death threats, serves as the basis for this film of the same title by Matteo Garrone (“The Embalmer”). And while the adaptation of “Gomorrah” obviously can’t match the breadth of the original, it certainly captures the brutal, take-no-prisoners tone of the expose.

The tack that Garrone has taken in translating the book to the screen is to focus on five narrative strands that, taken together with an overarching war for power among hostile factions, offer a tantalizing glimpse into the workings of the Camorra families that make up the Neapolitan “mafia,” an organization that reaps enormous profits from such operations as drug-running and phony knock-offs of designer fashions while controlling whole areas of the city and their unfortunate residents.

One thread involves a slick mobster named Franco (Toni Servillo), who specializes in deals to bury toxic wastes from the north in Campanian quarries and employs Roberto (Carmine Paternoster), a young up-and-comer, as his aide. Another concentrates on organization tailor Pasquale (Salvatore Cantalupo), who makes the mistake of agreeing to teach his techniques to the workers in a sweat shot run by Chinese immigrants, thereby endangering his own future, as well as that of his boss Iavarone (Gigio Morra). A third figure is Don Ciro (Giangelice Imparato), a meek organization money-man who delivers payments to mob families but finds himself threatened by the outbreak of violence among the crew’s warring families.

One weakness many will feel in “Gomorrah,” in fact—though it’s clearly an artistic choice—is its failure to make the specifics of that war very clear. In a haunting initial sequence we’re shown the assassination of a group of bigwigs in a tanning salon, but otherwise the conflict stays in the background except when unexplained gun battles and break-ins intrude into the streets and supposed safe-houses in the stories of the underlings on whom Garrone concentrates.

The remaining two plot strands involve outsiders, or more properly wannabes. One centers on thirteen-year old Toto (Salvatore Abruzzese), who delivers groceries within the mob-controlled housing complexes but seeks to become a foot-soldier in the organization—a desire that, in a shattering penultimate scene, sees him cross the line from cute to committed. And the other’s subjects are gruff Marco (Marco Macor) and stringbean Ciro (Ciro Petrone), a couple of goofy adolescents devoted to De Palma’s “Scarface” who aim at going it alone against the Camorra families—a decision that makes them irritants to the real powers in the region and leads to a horrifyingly matter-of-fact conclusion to the film. (The only ray of hope is provided by a decision taken by Roberto.)

What Garrone is aiming at here is obviously not a full portrait of the Neapolitan underworld but a tapestry that, by concentrating on a few examples, suggests the ungodly whole. Within the gritty, naturalistic framework captured on location by cinematographer Marco Onorato, the actors all deliver solid performances that range from Imparato’s querulous mousiness to the wild-eyed braggadocio of Macor and Petrone.

“Gommorah” can’t serve as a replacement for Saviano’s book. But by avoiding the conventions of gangster movies, it presents a slice of the ghastly reality of life in the crime-infested areas of Naples that has remarkable authenticity and immediacy. It’s a bleak and sobering film, but a very good one.