You can’t stay in business for as long as (our September Bookstore of the Month) Seattle Mystery Bookshop has without becoming really, really good at a thing or two. The most readily apparent sign of the bookstore’s excellence is in its selection, which I wrote about last week. The selection is really quite impressive — the shelves of Seattle Mystery Bookshop display a stock that is comprehensive enough to please the most deeply OCD mystery nerd and yet welcoming enough to appeal to a novice browser who has never before considered reading a mystery novel.

But the store’s not-so-secret weapon is its comprehensive understanding of the mystery genre, which it puts to great use as a tireless engine of book recommendations. A sign on the front counter as you’re walking in to Seattle Mystery Bookshop reads, “for mystery lovers who know what they want and for those who haven’t a clue!” That’s about right.

One of the store’s greatest resources is its seasonal list of new arrivals, which arrives in newsletter form and is consistently updated on their website. The list is broken out into subsections including local authors, new in paperback, historical books, international mysteries, and so on. Elsewhere on the site you’ll find long lists of staff picks to give you a sense of which booksellers’ tastes most align with your own. With its combined decades of bookselling experience behind it, the website has got to be one of the best online resources for mystery-lovers.

The real magic happens, of course, when you visit the store in person. Drop by at any random hour and you’ll see customers get connected with books that no algorithm would retrieve. The ever-changing displays provide a passive form of connection: one woman picks up Leonie Swann’s delightful Three Bags Full, about a herd of sheep trying to solve their shepherd’s murder, from a display of light-hearted mysteries.

But other pairings are more intentional. A young couple buys the latest volume of an urban fantasy series from bookseller Adele, mentioning offhandedly that it’s the only series of prose novels their autistic son is interested in reading. At that, Fran asks the couple to wait and disappears into the store for a quarter-minute, returning with a copy of Mark Haddon’s The Curious Incident of the Dog in the Night-Time, a mystery narrated by a young autistic boy. The couple are effusive in their thanks, saying that they might have to come back and buy a second copy because their reading-addicted daughter will likely grab hold of the book and not let go.

I decided to put the recommendation engine to work. I tell Fran and Adele about one of my favorite reading experiences: one morning a long time ago, I sat down to read a book from Ed McBain’s 87th Precinct series. I was entranced by both the mystery — it involved The Deaf Man, a recurring antagonist who plagues the 87th Precinct with elaborate, almost super-villainous schemes — and by McBain’s writing voice, which was short, and punchy and, it turns out, addictive. I finished the book in a couple hours and wanted more. I walked up to Twice Sold Tales, bought another Ed McBain mystery, took it home, sat down, and read that one from beginning to end, too. Then I returned to Twice Sold Tales again, bought another Ed McBain mystery, read that one from cover to cover, and then I ordered a large pepperoni pizza, ate it all by myself, and fell asleep. It was one of my favorite days. Do they have any recommendations for McBain-like thrillers, written in staccato sentences? Bonus points for a little bit of levity — McBain had a great, underrated sense of humor.

Without a single step wasted, Adele leads me to The Life and Death of Bobby Z, a novel written by Don Winslow. Get a load of these opening paragraphs:

Here’s how Tim Kearney gets to be the legendary Bobby Z.

How Tim Kearney gets to be Bobby Z is that he sharpens a license plate to a razor’s edge and draws it across the throat of a humongous Hell’s Angel named Stinkdog, making Stinkdog instantly dead and a DEA agent named Tad Gruzsa instantly happy.

“That’ll make him a lot easier to persuade,” Gruzsa says when he hears about it, meaning Kearney, of course, because Stinkdog is beyond persuasion by that point.

Sold! I ask if I should read Winslow’s latest, The Cabal, which is earning rave reviews everywhere. Adele gasps. “You haven’t read The Cabal?” I admit that not only have I not read The Cabal, but I haven’t read the novel that preceded it, The Power of the Dog, either. I ask if I should just pick up The Cabal. Adele shakes her head. “You really won’t get it without reading The Power of the Dog first.”

But I have another question: those mysteries that I like, the ones with the short, punchy sentences — McBain, Elmore Leonard — why are they always referred to as “masculine” books? Surely there are women authors who have a similar style? Fran and Adele both light up and lead to me Kelli Stanley’s San Francisco-set novel City of Dragons, a Hammett-like historical thriller that opens with a bang: “Miranda didn’t hear the sound he made when his face hit the sidewalk.”

And sold again.

From a memory of a terrific reading experience, Adele and Fran guided me to two books that I never otherwise would’ve encountered. On a certain online book retailer, the recommendations for those who look up McBain are Go Set a Watchman, the newest Michael Connelly mystery, and The Girl in the Spider’s Web, none of which are very appealing to first-time readers and none of which necessarily seem appealing to McBain fanatics. When it comes to suggested reading, people are in no danger of being replaced, John Henry-like, by algorithms. And when it comes to personally suggested reading, Seattle Mystery Bookshop has some of the best humans in the business.