If there’s an actor working today with more of a born “poker face” than Oscar Isaac, I’d be terrified playing cards against him. The sleepy, hooded eyes give him a resting blank-face – serious, impassive and never giving anything away.

So he’s well-cast as “The Card Counter,” a dour and guilt-ridden on-the-road-with-a-gambler tale from Paul Schrader. Schrader (“Affliction,” “Auto Focus” and the recent “First Reformed”) is the cinema’s poster boy for the expression, “An artist is someone who pounds the same nail, over and over again.” Here, his favorite themes of guilt, penance and possible redemption play out not at the card tables, but in who our hero chooses to take on the road with him.

No, it’s not about “card counting,” a trick to help a player even the odds in blackjack. It’s not even about the card game that ate America, Texas Hold’em, which dominates the card playing scenes. It’s about how the gambler who goes by William Tell found the time to master card counting, and the psychic cost of the crime that put him in jail, learning to memorize and properly value the cards remaining in a dealer’s shoe at the blackjack table.

Schrader turns this ex-con’s odyssey through his past with “the kid” (Tye Sheridan) who may have “awakened” his shot at redemption into an ungainly parable with abrupt, impulsive decisions and twists, banal, repetitive dialogue and lots of beautifully hard-boiled voice-over narration.

Tell got out of prison and hit the road, playing to win “with modest goals,” card-counting but never so that he takes big pots from any of the scores of casinos he passes through. He’s doing something they frown on, but never takes them to the cleaners. They let it slide.

He explains card-counting in some detail, breaks down the house advantage (odds) that he’s battling against, preaches his ethos of “bet small, win small” and reveals that “the safest bet for the novice gambler” is betting red or black in roulette.

He dresses simply, keeps his socializing to a minimum — “I’ve met enough people.” — and doesn’t give up his secrets to anybody, especially the vivacious fellow gambler LaLinda (Tiffany Haddish) who wants to get friendly. Card counter?

“I’m not that smart.”

But what happens at casinos attached to resorts? Conventions. That’s where Will ducks into a law enforcement convention’s presentation by an interrogation software huckster (Willem Dafoe). That’s where he meets the kid, who recognizes him. That’s where we figure out how the card counter ended up in prison with years of spare time to master his trade.

He was at Abu Ghraib, the infamous Iraqi prison where soldiers like him posed for photos while torturing Arab prisoners. He ended up in a military prison, while the “civilian contractors” (Dafoe) in charge went on to their next “enhanced interrogation” hustle.

“The Card Counter” finds himself compelled to accept the standing offer of having investors, arranged by LaLinda, “stake” him. He feels the need to give some guidance to the kid, who was collateral damage in what happened over there. Maybe it’s time he took his shot at “celebrity gambling,” with The World Series of Poker Tour as his goal.

Schrader dispenses with a lot of niceties to zero in on his major themes here. Script requirements trump realism — characters making decisions in character — time and again.

While Isaac and Haddish have decent, flirty rapport, there’s little between Sheridan and Isaac that feels real or organic. The Big Fat Metaphor — the player has taken the poker name “William Tell” and this kid could be the son whose head William Tell’s to shoot an apple off of — is supposed to account for that, I suppose.

The voice-over narration does the heavy lifting here. “There’s a weight a man can accrue. The weight created by his past actions. It’s a weight which can never be removed.”

But as Schrader wrestles with that weight and ponders “Is there an end to punishment?” the viewer can wonder if he had the answer before rolling camera, and if not, that might explain the clumsy third act.

“The Card Counter” is a drama in which you can appreciate the ambition and effort — tying the purgatory of gambling to past crimes against humanity — without ignoring the fact that it doesn’t come off.

There’s one great detail — Tell’s ritual uncluttering and cloth-wrapping his cheap motel rooms. And we can’t help but notice he brings two suitcases with him everywhere.

But the other characters are barely so much as sketched in, and Sheridan’s flat performance has only the faintest hint of “rescue me, Mr. Gambler” in it.

The clever deployment of distorting fish-eye lens effects to take us into Will’s nightmares is the flashiest effect Schrader has used since “Cat People.”

Schrader’s made a long meditation on something that’s right up his alley, and it still feels incomplete while it’s in progress, and even in the final reckoning.

Rating: R for some disturbing violence, graphic nudity, language and brief sexuality.

Cast: Oscar Isaac, Tiffany Haddish, Tye Sheridan and Willem Dafoe.

Credits: Scripted and directed by Paul Schrader. A Focus Features release.

Running time: 1:51