“The Rum Diary,” based on the Hunter S. Thompson novel, stars Johnny Depp as an American writer whose self-imposed exile to Puerto Rico in 1960 falls short of his utopian dreams when he gets caught in the crossfire between the island’s local natives and greedy expatriates. Directed by Bruce Robinson, not even the lush Caribbean scenery or Hollywood heavyweights can quite make up for a story as vapid as the corrupt ruling class that Depp’s character ultimately tries to take down.

Paul Kemp (Depp) is a failed novelist with a drinking problem when he arrives in San Juan to begin writing for the English-language San Juan Star, a daily newspaper staffed with misfits and, unbeknownst to Kemp, on the verge of financial collapse. After an ill-fated first meeting, the Star’s high-strung editor relegates Kemp to writing horoscopes, a mindless task that grants the writer more free time to indulge in what the island has to offer – namely, as the title suggests, rum. Teaming up with photographer Bob Sala (Michael Rispoli) and religious correspondent Moburg (Giovanni Ribisi), Kemp embarks on a debauched series of misadventures that include cockfighting, spitting fire at a cop and, subsequently, getting thrown in jail.

But between bouts of drunken tomfoolery, a chance encounter with real estate-mogul Hal Sanderson (Aaron Echkart) threatens to constrict Kemp’s carefree lifestyle. Against Sala’s advice, Kemp agrees to do some spin work on behalf of Sanderson’s latest project, which he soon realizes will have serious repercussions for the local population and environment. Extracting himself from Sanderson’s web of influence proves difficult, however, especially as Kemp has fallen head-over-heels for Sanderson’s femme fatale girlfriend Chenault (Amber Heard).

While the cast features a well-balanced mix of A-listers and up-and-comers, the film’s weak writing fails to provide them with anything substantial. From the outset, Depp plays the mumbling, bumbling schmuck well, but in such a way that makes his sudden transformation into a “serious writer” in the final act implausible. With the exception of Ribisi, who steals every scene he’s in as the supremely sloppy and barely functioning alcoholic Moburg, we are left with a collection of bland characters capable of delivering the occasional one-liner but overall lacking in depth.

“The Rum Diary” plays like a series of missed opportunities, not just in regard to the talent involved but also within the context of the story. Set in mid-20th century Puerto Rico, it barely scratches the surface on the racial tensions, political unrest, corporate greed and corruption that were rampant on the island, opting instead to focus on the glitz and glamour of the elite. Thus, for a story purportedly centered on indulgence, it feels oddly restrained, which is unfortunate given Thompson’s personal life and his legacy as a writer.

Undeniably stylish but ultimately just plain silly, “The Rum Diary” is not unlike a night of heavy drinking – aimless and, in the big scheme of things, doomed to fade to the recesses of memory almost as soon as it passes.