It is a stylish, savage world of nattily dressed men in fedoras and armed with sub-machine guns.  It is an iconic element of American movies: the period gangster film. There have been American period gangster films set in cities such as New York, Los Angeles and Chicago—but never one set in sleepy Ybor, Tampa Bay, Florida.

That is one of the many unusual things about the 1920s crime film “Live by Night,” which is based on Dennis Lehane’s excellent 2012 novel.

It is the time of Prohibition, and small-time hood Joe Coughlin (Ben Affleck) leaves Boston to take over the rum bootlegging operation in Ybor, forcing him to deal with both other gangsters and law enforcement, in particular, the religious Chief Figgis (Chris Cooper).

In the process, Joe meets the beautiful Cuban boss Graciela (Zoe Saldana) and partners with the devoted Dion (Chris Messina from TV’s “The Mindy Project”). But as Joe continues his takeover, he is forced to ask himself just how much of a gangster is he. Is he ready to do all the things that are necessary to succeed? And just how long before his shady past catches up to him? “I don’t want to be a gangster,” Joe says. “I stopped kissing rings a long time ago.”

More than just another gangster film, “Live by Night” is the latest film directed by Affleck, after the 2012 Oscar Best Picture “Argo,” 2010’s “The Town” and 2007’s ” Gone Baby Gone” (notably also based on a Lehane novel). He also wrote the screenplays for the latter two.

Affleck buys completely into the concept of Joe as a reluctant criminal, deciding to go the subtle route. It’s a performance of small gestures and relatively few words, much like Affleck’s own performances in the two movies he’s acted in and directed, “Argo” and “The Town.”

It’s a study of a man caught between savagery and sublimation. More broadly, Cooper presents a man with serious contradictions. The best performance in “Live by Night” is the almost unrecognizable Messina as Dion, all quick trigger and genuine bewilderment.  The cast includes Elle Fanning, Sienna Miller and Brendan Gleeson.

“Live by Night” is a very pretty movie, with the brightly lit Florida locations contrasting with the darkness of its subject matter. The movie starts out very cautiously, introducing all the players and the conflicts. It is a very introspective gangster film as viewers are shown both sides of Joe’s inner conflict. This might grate on viewers who expect their gangster films to be killing fields from the beginning.

Then, in its third act, “Live by Night” turns inexorably, viciously violent, like a man broken or turned, lashing out with blades and bullets, the body count piling up as the story closes in on its end. For those seeking blood, there’s more than enough of it here. It’s like there are two completely different movies tied together.

There’s also a lot to look at. Production designer Jess Gonchor and costume designer Jacqueline West go the extra mile in recreating the 1920s-era setting, down to humble storefronts, flashy cars and wingtip shoes. Cinematographer Robert Richardson shoots the scenes with a sense of just how the bad hides behind the good, the black behind the bright.

Most of all, “Live by Night” gives viewers a fascinating glimpse into Affleck’s continuing development as a director. While the story of a gangster-gone-good has been told before, Affleck tells it sleekly, echoing themes familiar from “The Town.” It’s particularly interesting considering Affleck’s next project as director-actor is supposed to be “The Batman.” An unusual crime film, “Live by Night” mixes the stereotypical and the stylish in an alternately muted and menacing portrait of a man who finds out just how far his humanity can defy the gangster’s cursed life.

Warner Bros.’ “Live by Night” opens in cinemas on Jan. 18.