Credit: Entourage: Claudette Barius

The basic premise that’s made Entourage a success — young-stud actor making it big in L.A., accompanied by his three-man Queens posse serving as manager, cook, and driver — could, by now, have curdled into smugness and repetition. Yet its new third season is almost preposterously enjoyable. When we last left our fame-grubbing foursome, there was tension as Adrian Grenier’s Vince struggled through a tough shoot — James Cameron’s blockbuster adaptation of Aquaman — while his romantic life crumpled. The season peaked when his egomaniacal agent, Ari (Jeremy Piven, entering every scene as though shot out of a Glock), was fired from his top-line agency.

The show’s creator, Doug Ellin, seemed to paint himself into a corner. If in the new season Aquaman flops, Vince and Ari become pathetic losers; if the film floats to the top, Vince just gets richer and Ari gets quick, barely earned vindication. Without giving too much away, let’s just say Ellin has found a third path, with Vince and Ari, in parallel plots, set on hilariously satisfying journeys that reveal fresh aspects of their characters.

One of TV’s unlikelier protagonists, Vince is a vacant vessel — he’s got nothing going for him except a sweet smile and a breezy, what-me-worry? manner. But he’s a dubious superstar only until you realize how similar he is to a lot of real current stars. Is Tobey Maguire (whose Spider-Man opening box office figure becomes a key plot point in episode 2) or Orlando Bloom any less bloodless than Vince? Not for my popcorn money. While Entourage fans know the laughs will come from Kevin Dillon’s resolutely clueless Johnny Drama (Vince’s has-been half brother) and Jerry Ferrara as pudgy horndog Turtle, the soul of the series is Kevin Connolly’s Eric — the smart buddy whose worried skepticism permits Vince to stay cool.

As always, it’s not the main stories but the subplots — such as Ari trying to bully a cocky 13-year-old, the star of Young 21 Jump Street (genius detail!), who’s making the moves on his daughter — that reveal the darting wit of the show. When Drama, in next week’s episode, mentions how he lost his Harley — ”I had to hock it to Michael Madsen after a couple of bleak pilot seasons” — he compresses an entire, depressing substratum of showbiz existence into a mere 15 words.

Entourage remains one of HBO’s few fresh successes, and not just because it’s funny. Here’s my theory: Entourage attracts both the Sopranos crowd and HBO’s unpublicized viewership: the Real Sex and Taxicab Confessions watchers. Go to HBO’s Entourage bulletin boards and you’ll see there are scads of would-be Turtles and Johnny Dramas who dig the show. They’re livin’ its dream vicariously.