It might not be the best show on television, but I don't think there's any show I enjoy watching more than Justified, which premieres its fifth season on FX tonight.

Over the course of its four seasons (and the two episodes I've seen from season five), the FX drama has quietly emerged as the most riveting cop show on the air, distinguishing itself with a twisty narrative, a deep stable of characters, a unique rural setting, and an unmistakably original tone and voice. It is, beyond any doubt, the best adaptation of Elmore Leonard's work to date — which is all the more remarkable when you consider how few of its characters and plotlines originated in Leonard's stories.

The modern TV landscape is littered with series adapted from literary sources. HBO's Game of Thrones streamlines elements of George R.R. Martin's original novels, but rarely invents a character or storyline wholesale. AMC's The Walking Dead improvises more freely, but inevitably ends up circling back to its comic book source material (and usually to its detriment).

Justified is a different animal altogether: A TV show that knows exactly which parts of its source material it should use, which parts it should change, and which parts it should leave behind. And it's the last one that makes all the difference.

Justified protagonist Raylan Givens was first introduced to the world in Leonard's 1993 novel Pronto (which in 1997 was originally adapted into an all-but-forgotten TV movie, with James LeGros starring as Raylan). In 1995, Leonard revisited the character in Riding the Rap.

But Raylan didn't really come into his own until a 60-page novella called "Fire in the Hole," which was first published in 2004's story collection When the Women Come Out to Dance. Raylan, a Kentucky-born U.S. Marshal (and modern-day riff on the cowboy), towers over the rest of the characters in Pronto and Riding the Rap, but he's out of his element, tracking criminals in Miami and Italy. For all the strengths of those novels, it isn't until "Fire in the Hole" — which sends him back to crime-riddled Harlan County — that Raylan truly comes to life.

Leonard, who died of complications from a stroke in August, was no purist about his work. His favorite adaptation of one of his stories was Quentin Tarantino's Jackie Brown, a riff on his Rum Punch that changed, among many other things, the name and race of its protagonist. Leonard did have his occasional sticking points; according to showrunner Graham Yost, it took Leonard a while to accept the white cowboy hat Raylan wears on Justified, which has a larger brim than the Businessman's Stetson he had originally imagined. But Leonard, who served as an executive producer on the show, also counted himself among its fans; in the weeks leading up to the premiere of Justified's second season, he wrote that "a lot of actors have done [his] characters over the years, and there have been some good ones — but nobody in this world as perfect as [Justified's Timothy Olyphant]." The compliment is all the more striking because Raylan, as played by Olyphant, doesn't bear a particularly strong resemblance to the character Leonard originally wrote.

What Leonard and the creative team behind Justified understood is that fidelity to source material isn't necessarily the best way — or even the most accurate way — to capture the heart of a story. Raylan's ex-wife, Winona (Natalie Zea), plays a pivotal role in Justified's earlier seasons. But Winona barely registers in Leonard's original novels; instead, he saddles the former couple with two unseen young sons (and makes Raylan, by extension, a deadbeat dad).

In Justified, Raylan's father, Arlo, is a notorious criminal and a reliable antagonist whose cruelty led Raylan to join the Marshals Service in the first place; in the novels, Raylan briefly explains that his father died in a coal mine long before the novels began.

Most significantly, the single, pivotal decision that propelled Justified from enjoyable diversion to top-tier TV drama was wholly original to the show — and it almost didn't happen. Just as in "Fire in the Hole," Boyd Crowder (Walton Goggins) — a lowlife criminal who carries himself like a Shakespearean king, delivering grand speeches in a delicate, highly enunciated Southern drawl — was slated to be shot to death by Raylan at the end of Justified's pilot. A belated rewrite gave Boyd a reprieve, and by the end of the season, he had evolved into a kind of second protagonist who remains as essential to the show as Raylan himself.

Unfortunately, that kind of dramatic reinterpretation is getting rarer and rarer all the time. We live in an age of hard-core fandom, in which the release of any movie or TV show with a built-in fan base spawns dozens of blogs that meticulously document (and generally complain about) all the changes that were made. But Justified could never have evolved into the brilliant, tense drama it has become without the collective willingness to treat Leonard's hundreds of pages of material as a mere jumping-off point.

Justified's unique successes haven't been echoed by any TV adaptation since, but the possibility for reinterpretation remains as enticing as ever. If creators and fans alike were willing to embrace the spirit — and not just the letter — of the stories they love, the TV landscape would be much richer for it.