Using super-zoomed and slow-downed footage, the trailer revisits Nucky's execution of his one-time protege Darmody, who betrayed his former mentor in a political coup led by the Commodore.
Though the trailer doesn't offer much in the way of new footage, it does add two symbolic developments to the scene. As Nucky looks down on Jimmy's dead body, both his wedding ring and signature carnation lapel fall off his body. If one represents his new marriage to Margaret Schroeder -- who secretly sold his land holdings to the church -- and the other represents his political career, then it seems clear that both are headed for more turmoil in Season 3.
The trailer closes by flashing a quote Jimmy told Nucky back in Season 1: "You can't be a half gangster." It's clear which path Nucky has chosen.
In an interview that appeared on The Huffington Post in February, "Boardwalk" creator Terrence Winter described where Season 3 was heading:
We're moving into 1923 when the Twenties really became the 'Roaring Twenties.' The economy began to boom and this became the Flapper Era. The parallels between then and now are obvious because that period mirrors the world we live in today. Prohibition, for instance, is the model for the illegal drug business; it's what made millionaires out of gangsters. People were buying political favors, and big business controlled everything.
"Boardwalk Empire" premieres Sun., Sept. 16 at 9 p.m. ET on HBO.