The season 4 trailer of Boardwalk Empire showcases several spoilers, including the introduction of Nucky Thompson's new nemesis and the rise of Al Capone.

Season 4 takes place in 1924, at the beginning of the jazz era, according to the show's creator Terence Winter. Jazz clubs were a big business back then, and it seems that a gangster named Dr. Narcisse wants a piece of Nucky and Chalky's business on the Atlantic City boardwalk. The show's new character hails from Harlem, which was the epicenter for Jazz during that era. He is the first black character of such prominence in the show, since Chalky was introduced in season 1.

"Do you know what power is? It is freedom and control over men who are lesser than you. This is my business," Narcisse says in the opening of the season 4 trailer.

The preview showcases other notable gangsters, such as Arnold Rothstein, who seem to acknowledge Narcisse's clout, as the talk about him and engage in business deals with the Harlem gangster.

In America's other gangster hub of Chicago, Al Capone seems to be enjoying a meteoric, while destructive, rise to power.

"Do you want to take on the Chicago police? They'll send an army!" Capone's one-time boss Johnny Torrio says to him in the trailer.

Torrio's admonition comes after a scene where Capone walks up to a policeman, who is reading a newspaper, and proceeds to shoot him in broad daylight. Along with the Chicago police, Capone has another adversary in mobster Dean O'Bannion. In once scene, O'Bannion and Capone confront each other with their respective crews, as they prepare for a potential street brawl.

The first episode of season 4 of Boardwalk Empire premiers on Sunday, Sept. 8 at 9 p.m. ET on HBO.