The first moments of the third season of Boardwalk Empire — returning to HBO this Sunday at 9 p.m. EST — introduce a new antagonist, Gyp Rosetti. As played by the criminally underrated Bobby Cannavale, Rosetti is a high-living lowlife, a Sicilian thug wrapped up in bespoke finery. The biggest mistake you can make with Rosetti is dealing with him in the first place. But the second-biggest is making him feel dumb. (This is a slippery business, because Rosetti, while street-smart, is decidedly book-stupid.) He desperately wants to be a gentleman, but he’s never more than a gangster. As an unfortunate Samaritan learns the hard way — like, tire-iron hard — Rosetti has a tendency to explode into shocking violence in order to be taken seriously. In other words, he’s the perfect avatar for Boardwalk Empire, a puffed-up show that drowns its myriad shortcomings in an ocean of booze and blood. It’s the televised equivalent of an empty suit.