As a genre, mysteries have never really appealed to me; I find most of them formulaic, predictable, and, to be honest, boring. There are a few I’ve enjoyed, though — Caleb Carr’s “The Alienist” and Rhys Bowen’s Molly Murphy books, for example. But my current favorite mystery author — I’d even go so far as to call him one of my favorite writers right now — is Will Thomas, who resides just outside Tulsa.

His most recent book, “The Hellfire Conspiracy,” is the fourth in his Barker-Llewelyn series, preceded by “Some Danger Involved,” “To Kingdom Come” and “The Limehouse Text.”

Cyrus Barker is a private enquiry agent — that’s a detective, to you and me — and Thomas Llewelyn his trusty assistant. In this installment, young girls in Victorian London are disappearing and then turning up dead, the purported victims of a white-slave ring. It falls to the duo to discover who is behind the heinous crimes.

Barker is a man of many complexities — one could even say contradictions. Although a skilled fighter, he is not particularly fond of violence. He is a man of simple tastes but employs a French chef. A Baptist tabernacle is his destination every Sunday, yet he has friends, employees and colleagues of diverse cultures and religions.

An Englishman through and through, Barker surrounds himself with all things Chinese, a holdover from his shadowy youth spent abroad. He practices martial arts, insists on drinking only green tea and employs a team of gardeners to maintain his property’s exquisite landscaping. He even has a Pekinese — an extremely rare dog to have at the time.

His associate, Thomas Llewelyn, was a down-on-his luck Welshman when the reader and Barker first met him in “Some Danger Involved.” Although he escaped his humble beginnings to earn a quality university education, he was a man whose life was in shambles. He’d served time in prison after being framed; while he was unjustly imprisoned, his beloved wife died from consumption. He was a desperate, hungry man in a raggedy suit, but Barker took a liking to him and hired him.

And a good match they are. To borrow from the Chinese culture that Barker regards so highly, they are yin and yang. Barker is tall and muscular, while Thomas is short and wiry — an old nemesis of Llewelyn’s refers to him as a “Welsh terrier” in “The Hellfire Conspiracy.” Barker has the esoteric knowledge gleaned from his mysterious past, but Llewelyn has the book learning that frequently proves invaluable. Barker is level-headed, while Llewelyn is led by his heart — especially where the ladies are concerned.

Will Thomas’s background — he spent five years working the reference desk and handling adult programming at a public library — is evident in his writing, which is rich in detail, from the historical figures that populate his books, to the geography of London, to the intricacies of Cockney street slang. Many people mistakenly think the Victorian Age was simply a time of repression and great propriety; Thomas’s London reflects the reality. It is a place where prostitution, crime and grinding poverty are widespread.

And minorities play key roles: Key characters throughout the series are Chinese or Jewish. Their cultures and religions are treated with respect and are far from stereotyped. Barker’s butler, Jacob Maccabee, or “Mac” for short, might sport a yarmulke, but he brews his own stout and is quick to brandish his trusty shotgun when the occasion calls for it.

For me, the plot of “The Hellfire Conspiracy” is secondary. The appeal is the characters, with their keen minds and mad fighting skills, as well as their world rich in diversity. To see this diversity through Llewelyn’s eyes is a treat. He is frequently shocked, sometimes amused or frightened, but open to new experiences.

I’ve devoured every book by Will Thomas thus far, and I look forward to many more. (My dream is actually to entice him to the Joplin Public Library for a program.) For mysteries that are a welcome break from the likes of Janet Evanovich or J. D. Robb, check out this Oklahoman’s Barker and Llewelyn series.

Lisa E. Brown is the administrative assistant at the Joplin Public Library.