When every channel has a crime show (or three), “Castle” could easily be overlooked as just another murder drama. However, its characters, which are as complex as the cases they crack, and its startling mysteries, which often blend the fanciful— fairytales or CIA conspiracies—with murder, make it anything but mundane.

In the pilot “Flowers For Your Grave,” which aired on March 9, 2009, Richard Castle (Nathan Fillion), a charismatic mystery novelist, struggles with writer’s block while Detective Kate Beckett (Stana Katic) searches for a serial killer whose murders are mysteriously similar to the crimes in Castle’s works. After bringing Castle in for questioning, Beckett becomes his unwilling muse, as he begins shadowing her for inspiration for his writing. In a far-fetched twist of fate, his talent for profiling and spotting clues, a result of his work as a novelist, soon makes Castle an essential member of the homicide squad. His detective skills surpass even Beckett’s. Her main police priorities, which consist of intimidating suspects and engaging in gunfights, seem to initially belittle her potential as a character.

Beckett acts as the “brawn” of the duo, hiding behind a harsh, “street-smart” shell. As a domineering female boss, she orders around her fellow detectives Owen (Seamus Dever) and Esposito (Jon Huertas), two static characters who serve mostly to give punch lines than to shape plot. Beckett’s stereotypical character traits are too overdone to be interesting. Her antics are even duller when compared to the theatrics of Castle, making it clear why he is the eponymous hero. However, Beckett does have her moments. In the episode “Rise,” Katic gives her best performance in the series, depicting Beckett’s mental unraveling and tense interactions due to post-traumatic stress disorder (PTSD) with gut-wrenching intensity and emotion. By slowly shedding her clichéd façade, Beckett becomes three-dimensional and distinguishes herself among the other tough love detectives scattered throughout TV land.

Nevertheless, Castle remains the wildly entertaining star, largely due to Fillion’s superb acting. In a potentially gritty drama, his juvenility and charm effortlessly brighten the otherwise dark atmosphere. Unlike the detectives who display about as much emotion as the murder victims they investigate, Castle is babyish and even treated as such by his mature, academic daughter Alexis (Molly Quinn). However, his new gig with the police does force him to grow up a little, an essential stepping stone for a man seemingly stuck in Neverland. As he steps up in “Rise” to protect Beckett from her downward spiral, his personality develops.

As would be expected in any television show with opposite gender leads, Castle and Beckett have noticeable sexual tension from the start. At first, the duo’s romantic friction lent little to the show besides laughs, fueled by superficial flirting and jealousy. As shown by his string of girlfriends and bawdy nature, Castle is a cheeky playboy. In the episode “Deep in Death,” he even goes as far as to invite strippers to Beckett’s precinct. Because of this consistently raunchy behavior, it’s hard to tell whether his attention to her is a game or sincere affection, creating a major annoyance early on in the show. But by giving her some much-needed space to deal with her PTSD, Castle manages to forge a deeper connection with Beckett, who is slowly realizing that she needs him a lot more than she had originally thought.

The romance is exciting; however, the plot tends to stagnate as it grows, falling into a pattern like many of its crime drama kin have done: an intriguing case turns up that sparks Castle’s curiosity. The pair works through several suspects before finding the “guilty” party, always revealed to be innocent. After a previously obscured clue prompts the cunning detective Castle to realize their mistake, another chase for the real culprit ensues and Beckett triumphantly captures the criminal. But the inventiveness of the crimes themselves, which have involved ghosts, tiger-smuggling rings, and alien encounters, makes the show worth watching every week, despite its formulaic approach.

If you’re looking for an accurate portrayal of life as a murder detective, “Castle” may not be for you. The wild plots add to the allure of “Castle,” but they also detract from its believability. In only four seasons, there have been dozens of kidnappings and near-death encounters, but few realistic consequences. Castle and Beckett frequently escape the clutches of death only to plunge back into their work without recovery, giving the impression that these dramatic events don’t faze them in the slightest. This lack of response to life-altering moments makes the plot twists seem pointlessly far-fetched. However, if you accept it for what it is, the characterization is solid and intriguing.

This lesser known show blends crime with romance, drama, comedy, and the realistic world of homicide deductions created by the wit of a best-selling author. Although its nature is predictable and the characters are occasionally flawed, its uniqueness mandates trying an episode or two. Airing on ABC at 10 p.m., “Castle” is a world of ingenuity rooted in the classic murder mystery mold.