Scrolling through primetime TV options, I came upon a show called “The Sinner” and read a capsule description that began “A troubled detective returns to his hometown to investigate…” and there was no need to read further.

Of course, the detective was troubled. Aren’t they all? And yet they didn’t start that way. Poe’s Dupin was a model of rationality. Detective Bucket in “Bleak House” was the precursor of legions of tough-minded street cops who have seen it all. Hercule Poirot is finicky about his appearance, but much of that can be laid to English contempt for continental fops. Miss Marple is cozy and razor sharp, but far from troubled.

You can’t help but notice who I’m leaving out. Sherlock. The archetypal troubled detective — an antisocial, supercilious, easily bored genius who treats his ennui with violin solos and a drug habit. But even if he provided the template for the majority of later sleuths, most imitated his ratiocination not his psychopathology.

Morse substituted opera and beer. Nero Wolfe was more like Sherlock’s brother Mycroft. He never stirred from his brownstone where he ate gourmet meals and tended his orchids, but that’s merely mild eccentricity, like Lord Peter Whimsey’s dilettantism. Sam Spade, Phillip Marlowe and their heir, Lew Archer, were tough guys at home on the mean streets, but no more irregular than your average cop.

Originally the minor oddities of detectives were simply window dressing by authors trying to humanize their main character since their adventures were essentially solving puzzles, and the other chess pieces in the game were stock types from central casting, as in Clue.

Now, however, the oddities of detectives have begun to elbow aside the puzzle. They are the puzzle. You now seem scarcely qualified to lift a fingerprint if you aren’t certifiable. I suppose this was inevitable when even mob bosses were seeing a shrink.

Admittedly, the British are still more inclined to keep a stiff upper lip, especially the men. Their usual problem is being too irregular to maintain a marriage, household, or children. Women detectives, however, seem to be increasingly beset by angst, loneliness, neuroses and substance abuse. Helen Mirren in “Prime Suspect” was a trailblazer for women’s equality insofar as pathology was concerned.

A turning point in the process of highlighting the detective’s disorders may have been Jimmy Stewart’s vertigo in “Vertigo,” around which the entire plot dizzily revolved. Soon you could barely investigate a crime without having a disabling flaw you bravely soldier on in spite of. The updated Sherlocks played by Jonny Lee Miller and Benedict Cumberbatch often put the ills of their character centerstage.

Monk was OCD. And detectives who are idiot savants or somewhere on the Asperger’s spectrum are now a dime a dozen, in part because of the Scandinavian series “The Bridge” which forced odd couple detectives from two countries to work together on a case. The female character lacked skills at social interaction and had a restricted range of interests but excelled at obsessive attention to a case. This was replicated by in remakes set on the Mexican-U.S. border (also called “The Bridge”) and on both sides of the Chunnel (“The Tunnel”) starring Diane Kruger and Clemence Poesy, respectively.

As long ago as 1965, Kingsley Amis was astute enough to describe the character of James Bond (books, not movies), and to identify his origin. Amis said Bond was “lonely, melancholy, of fine natural physique, which has become in some way ravaged…of a cold or cynical veneer, above all enigmatic, in possession of a sinister secret.”

This figure dates from 1818 as Childe Harold and has been popping up ever since, beginning with the Bronte sisters. He is the Byronic hero, and many detectives are his offspring. Often they are lone wolves, even if they work for an organization, though more often perhaps are private eyes. Reacher is an extreme case, in that he might easily be mistaken for a hobo since he has no fixed abode or possessions and has been know to travel by Greyhound. One, Wallander, even ends his career as a sleuth by adding a further isolating trait by becoming afflicted with dementia.

Many of these wounded figures have suffered an insupportable grief, a terrible loss, often a lost or murdered love — Gabriel Allon, James Bond, Bosch, Rebus. It clearly isn’t wise for a woman to cozy up to such a character. It is reasonable to see the weakness of these figures for drink or drugs as a means they have adopted to self-medicate their sorrow.

This is not the only way to cope. In the short-lived “Life,” starring Damian Lewis as Charlie Crews, an L.A. cop was framed and spent years in prison before emerging cleared and richly compensated for the mistake. He could live a life of luxury, but he insists on returning to duty. He is a changed man, however, having survived incarceration by embracing Zen Buddhism. This makes him as baffling to his new partner as if he had Aspergers or OCD.

Other detectives suffer from what might be called delusions of grandeur or quixotism. They imagine themselves to be pure knights righting wrongs, and not surprisingly don’t fit into the usual cop shop since they do not cut corners or settle for a tie score against the bad guys. Again, Reacher is an extreme case of this, and Travis McGee a more cheerful version. He only takes cases when he needs the dough and spots something worth crusading for. Bosch and Rebus occupy the more common middle ground. They are good cops, but sticklers for justice who keep running afoul of the suits and getting suspended for being too incorruptible.

Finally, in “Killing Eve,” we encounter a really interesting psychodynamic. Our heroine is an intelligence operative who has the usual quirks, but who becomes obsessed with similar murders that seem to point to a brilliant assassin. She identifies another women as the likely culprit and begins to develop an obsession that verges on a crush for the killer. The killer is bemused by the attention and reciprocates the feeling of fascination.

Wow! It’s a folie a deux. We’ve never seen anything like that before. Or have we? What about “The Woman,” the dominatrix, Irene Adler, Sherlock’s femme fatale? It has been said that all philosophy is just footnotes to Plato. Hemingway said all modern American literature came out of one book, “Huckleberry Finn.” And maybe we just have to admit that all detective fiction begins and ends at 221B Baker Street.