In the first episode, “Flowers For Your Grave,” Rick Castle is at a major turning point in his career. As a murder mystery novelist who has just killed off his moneymaking main character, Derek Storm, he is now faced with every writer’s greatest fear—the blank page. Castle is finding it difficult to commit fingers to keyboard and hand in the next manuscript to his publisher, who just happens to be his ex-wife. With a three-week ultimatum issued by his frosty ex, Castle realizes he needs to find his next great character.

Enter Kate Beckett, New York Police Detective with looks of steel, but one guesses, a soft, gooey center. Taking Castle downtown, she grills him on two of his lesser-known novels as the police believe they are on the trail of a serial killer who is emulating Castle’s crime scenes. During this witty sparring match, we discover Castle has lived a less than a pious life, however, he always seems to worm his way out of any situation, which of course, annoys Beckett to no end. Because where would the fun—or the originality—be in that?

Castle is jazzed at the idea that he has a copycat, calling it the “criminal’s Cooperstown,” a mystery novelist’s hall of fame. By using more of that famous charm, Castle insinuates himself into Beckett’s investigation, calling in favors from the mayor and becoming buddies with her boss. With his famous smile and quirked left eyebrow, Castle is now part of the team.

With startling predictability, Beckett, et al. uncover one murderer who is so blatantly a red herring he practically glows before Castle pops their bubble by reminding Beckett that it’s not always that easy. Convinced that the perp they’ve identified is not the killer, Castle examines the case from his unique viewpoint, as a writer. “There’s always a story,” he tells Beckett more than once, and so, by breaking down the facts of the case into story points and characters, he realizes that the real murderer is someone else—just as Beckett reaches the same conclusion through police work and logical deduction.

This brings them back together and leads them to the real murderer who is also so obvious it’s painful. However, I will admit that the way they nailed him was a little different and I give the writers kudos for the twist. After apprehending the real bad guy (literally, as Castle possesses an inability to follow orders and ends up being held at gunpoint by the fleeing killer), Castle and Beckett part ways, much to Beckett’s relief …

… Only to be confronted with Castle’s mug once more as it’s revealed that Beckett is the inspiration for his next great literary character and he must do “research” to be sure he gets it right.

It isn’t any coincidence that the show ends with a shot of Castle’s charming grin or that it opens with Castle signing an autograph on the chest of a female fan. It’s also not a coincidence that Nathan Fillion did the talk show circuit last week sitting down with “Jimmy Kimmel,” “Good Morning America” and “The View” in the space of twelve hours. Nope, none of that is random, because what “Castle” has going for it is Nathan Fillion.

The guy’s charming. This isn’t a surprise to his long-term fans or the viewers who tuned in for the first time tonight. He perfected his comedic timing on “Two Guys and a Girl” and then solidified it—and showed off some serious dramatic skills—by embodying Captain Mal Reynolds, the space pirate with a heart of tarnished gold, on “Firefly.” And let’s not forget Doctor Pomatter in Waitress who was the most sympathetic adulterer we’ve seen for quite some time. Even as the vain, narcissistic superhero Captain Hammer in this summer’s surprise Internet sensation, “Dr. Horrible’s Sing-Along Blog,” we still loved him because when Nathan smiles, you think he’s smiling at you.

And that’s what the creators, Rob Bowman, Andrew W. Marlowe and Barry Schindel, are banking on. But the show won’t work if Fillion doesn’t have a strong female lead to captivate and they may have found her in Stana Katic. Fillion and Katic’s chemistry in the first episode is solid if not heartwarming. I’m not convinced I’ll ever buy an actual “relationship” developing between these two which is where the producers have got to be heading come season two. It’s where all male/female cop show pairings eventually end up. If you don’t believe me just take a look at “Moonlighting,” “The X-Files,” or “Scarecrow and Mrs. King.” Oh, or tune into “Bones” this May.

Like “Bones,” “Castle” relies on the charm of its lead characters to make the procedural aspect of the show interesting. It reminded me a bit of “Law & Order” with personality. Don’t get me wrong, the late Jerry Orbach had personality coming out his ears, but Fillion’s charisma is maybe more accessible. Or, let’s face it, just more fun to watch.

The production value of the show was uneven; the soundtrack was trying too hard to be fun, while some of the editing seemed like a blatant attempt to be “quirky.” The writing and acting should do this work for the producers; relying on external elements to tell the audience what the show is about, is a little like relying on a book jacket to tell you what the book’s about. The proof is the content, folks.

Despite “Castle’s” reliance on its two leads, the supporting cast should not be ignored. Susan Sullivan, a staple of television for decades, plays Castle’s boozy and loose mother with regal aplomb, however, how exactly she’ll endure week after week and not get old is a mystery. Castle’s 15-year-old daughter Alexis (Molly Quinn) has the potential to act not only as her father’s moral compass, but his emotional one as well. Seeing a character through the eyes of their child is an opportunity that should not be missed. And I think Quinn might be able to hold her own against Fillion’s magnetism.

Beckett’s police friends were all a little too marginal to really get a read on, although the forensics examiner, Lanie Parish (Tamala Jones), could be a lot of fun. She could also just be the clichéd best friend who tries to convince the uptight main character that the free-wheeling male lead really is a hottie and she deserves to let her hair down and go for it. I’m hoping she won’t be; I’m hoping they’ve got some more story for her, but I just thought I’d lay out the options.

The staying power of “Castle” will rely on three things: Nathan Fillion’s appeal; the relationship between Castle and Beckett; and the writing. There are dozens of procedurals on every day and repeats of “Law & Order” almost every hour; American TV viewers know their cop shows. Bringing something original and engaging to the screen will make or break “Castle” and chart its longevity.

So, how long will it last? Toward the end of the episode, Beckett complains that Castle is “like a nine-year-old on a sugar rush.”

Here’s hoping someone keeps the candy coming, because Nathan Fillion deserves a show and the pilot episode of “Castle” implies that it’s a show that deserves a chance.