Ideas that sound good on paper often belong on paper — like Showtime’s plan to offer hungry “Sopranos” fans an organized-crime drama to fill the void while we wait for its final season to start in January. It’s too bad, because the notion of “Brotherhood,” which makes its premiere this Sunday at 10 p.m., has the rich promise of a novel: Two brothers, a politician and a criminal, circle each other in a sordid world of petty crooks and lowlife government officials amid the corruption of Providence, R.I. But its failure to go beyond those obvious elements is just one reason why this “Sopranos” knockoff won’t win fans among those who swear by its inspiration.”Brotherhood” is perfectly decent dramatic fare in a genre that now demands greatness.

There’s a lot to enjoy in this 11-episode first season, particularly in the well-drawn relationship between Tommy Caffee, the “good” brother whose political star is on the rise, and his brother Mike, a low-level criminal whose motives often have less to do with money than loyalty. As one might expect, the characterizations aren’t simple; Tommy has been tempted by personal corruption just as Mike works his power for the good of his friends. But in a way, the show’s commitment to complexity is part of what makes it seem, in the end, so predictable. We’re meant to ask ourselves the most obvious question, again and again: Which of these brothers is good, and which is evil?

Maybe it’s impossible, at this point, to find truly original ground in the arena of organized crime; savvy viewers will quell their boredom by trying to decide whether “Brotherhood” derives more from Martin Scorsese or Francis Ford Coppola or David Chase. (The answer: It’s a three-way tie.) Scenes of violence and mayhem no longer shock us on television; when Mike cuts off someone’s ear and blood comes shooting out, only the weakest will wince. The rest of us have long since become immune to the shocks of mob violence. By the final episode, which draws heavily from “The Godfather” and “The Sopranos” in its use of a wedding as a backdrop for mob business, an audience in search of something fresh will have likely moved on.

If “Brotherhood” has any chance at all, it’s due to terrific and bold casting in the two main roles: Jason Clarke, an Australian actor best known for his appearance in “Rabbit Proof Fence,” inhabits the role of Tommy Caffee with a quiet, mysterious blankness that perfectly suits his embattled soul. Jason Isaacs, a British actor, executes a fresh take on the gangster with the heart of gold; he can kill with the best of them and yet be there when his alcoholic pal needs a helping hand. As Tommy’s pot-smoking wife, Eileen (Annabeth Gish), makes a memorable contrast to Edie Falco’s controlled Carmela Soprano, and Fionnula Flanagan plays the Caffee matriarch with the appropriate measure of sinister duplicity.

But even with its cast, “Brotherhood” can’t overcome its predictable script and conventional plot points. After 11 episodes, hearing Tommy Caffee say, “He’s my brother … I should be loyal,” to his wife, as an explanation of why he won’t cooperate with an investigation of his brother, gives some suggestion of the lack of subtlety on display. (As does Eileen’s response to Tommy: “Be loyal to me and the girls.”)

The creator of “Brotherhood,” Blake Masters, never manages to move beyond the Cain v.Abel concept that must have sold his pitch; there just aren’t enough twists and turns in their lives for us to care, week after week, about the family strains (and the mother) that pushed these brothers to the edge. It’s less reflective than “The Sopranos,” and that’s a loss for an audience trained, by Messrs. Coppola, Chase, and Scorsese, to look for the motives behind the criminal mind.These brothers could use a shrink, and it wouldn’t hurt the show, either.

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Last week’s great episode of “Entourage” and an even better one coming up this Sunday night at 10 p.m. — directly opposite the premiere of “Brotherhood” on Showtime — have jump-started the third season at last. HBO must not have been able to resist sending out these two great half-hours of television to critics in advance. After three weak episodes launched the “Entourage” third season, the producers found a fresh new story line that looks to be its best one yet. “Entourage” finally moves beyond the silliness of celebrity to delve into the real currency issues of fame — and dares, in the process, to touch on matters of how Hollywood really works. Vince Chase wants to use his “Aquaman” muscle to make a movie that matters, while the studio wants to force him into the sequel. The hardball negotiations between Vince and the studio come as close as television ever has to capturing the bluffs and bluster that comprise a big-time Hollywood movie deal. It’s a pleasure to have “Entourage” make the leap into something genuinely dramatic; the show was threatening to drown in its own superficiality. The art of the Hollywood deal has been a motif strangely absent from a show that celebrates agentry with such a passion; it’s good to see Ari Gold finally doing something for his commission, besides taking the boys out to dinner at the Grill.

dblum@nysun.com