Alternately conniving and seductive, the ensuing power dance between these two master manipulators puts “Nightmare Alley” right up there with “Sunset Boulevard” (with its sordid battle of the sexes), “There Will Be Blood” (where commerce clashes with religion) and other period studies of opposing forces. And true to the cynical essence of the noir genre, both sides are shown to be equally corrupt: The way Stan sees it, he and Lilith are in the same racket, leveraging what they know about the universal pillars of human desire — health, wealth, love — to give their customers false hope. “Fear is the key to human nature,” as Gresham observed, and both psychiatrists and spiritualists exploit it in their way (religion does too, though del Toro downplays that most damning dimension of Gresham’s critique).

Back at the carnival, Pete had advised Stan to steer clear of “spook shows,” where a mentalist pretends to commune with the dead. But Stan’s fatal flaw — the one most likely to trip him up — comes in the way this slick talker tries to compensate for his own sense of inadequacy by convincing himself that he’s superior to everyone else. A sworn teetotaler, Stan dismisses Pete as a drunk and figures he can fool gullible strangers into paying to speak with their dead lovers, sons and so forth. (Enter Richard Jenkins as a deeply damaged man with all the money in the world, looking to buy some peace of mind.) By the end, however, he’s hooked on booze and haunted by visions of his dead father — the nightmare alley of the film’s title.

There are few things more dangerous than a con man who believes his own spiel, and here, del Toro takes that dynamic to its inevitable conclusion. Once things escalate, the director can hardly resist a bit of the old ultra-violence — a weakness that infects nearly all his films, as he insists on pushing our faces into the gory, bone-crunching consequences of his characters’ behavior. He darkens some of the details from the book, so that the culprits “deserve” what’s coming to them, but for most audiences, the sight of mangled faces will be too much, especially after all the magnificent visuals del Toro and his creative team — especially DP Dan Laustsen, production designer Tamara Deverell and costume designer Luis Sequeira — have provided.

From re-creating a vintage circus with its pickled animal fetuses and hand-painted sideshow banners to evoking the stratospheric heights to which this social climber aspires, the movie ranks as the most stunning modern noir to behold since Brian De Palma’s “The Untouchables.” Dark as del Toro’s vision may be, it’s a glorious homage to an American experience all but lost to time. For centuries, carnivals of some kind offered an exotic alternative to small-town life, as customers willingly sacrificed their quarters for illicit thrills. And now that experience lives on, immortalized in a cautionary tale for the ages, its arc an elegant full circle, like the giant Ferris wheel that signals from afar that something wicked this way comes.