The Affair” capped an otherwise splendid first season in somewhat uninspired fashion. Yes, the Showtime series closed on a cliffhanger, one that creates a host of possibilities going forward, in an hour that also incorporated a couple of pretty major revelations. Yet the show’s murder-mystery — not just whodunit, but who got it done to them — has at times felt like its least compelling component, and the twists elevated that plot in a way that approximated less the confines of premium cable than the histrionics of ABC’s Sunday-night soaps.

At its core, the program’s terrific leads, Ruth Wilson and Dominic West, their characters’ torrid affair and its complications for all those surrounding them has unfolded in slow but absorbing fashion. That was augmented by the “Rashomon”-like device of having events recalled in the two characters’ alternate perspectives, with details often diverging in small but significant ways.

The finale, however (and SPOILER ALERT if you haven’t watched), not only moved the murder investigation into a new phase — with West’s Noah, having been caught in several damaging lies, being arrested — but also saw their individual recollections of a key encounter involving Wilson’s Alison and her husband Cole (Joshua Jackson) differ so wildly as to go beyond perception into the surreal.

It’s too bad, since the 10th episode started with promise, picking up some time after the previous hour, with Noah and Alison apart, and the former experiencing the life of a single man – and a promiscuous one at that – during his separation from his wife Helen (Maura Tierney, who has been especially strong since learning of Noah’s infidelity). The opening sequence, in fact, cleverly circled back to where the series began, reminding us that Noah had been tempted to stray before Alison and, in his mind anyway, had ample opportunities.

Acting on those impulses, moreover, boomeranged back on Noah, but in an unexpectedly helpful way: Getting him in trouble in his teaching job, which placed him on a kind of probation that allowed him to put the time to use finishing the second novel whose success had already been foreshadowed.

So far, so good. But then Noah pummeled Cole’s brother for impregnating his teenage daughter — or did he, since there were no fisticuffs in Alison’s account, just her husband training a gun on Noah and threatening to shoot him.

And then, the arrest for the brother’s death in what, the police have determined, wasn’t just a random hit-and-run accident but an act of revenge.

Obviously, “The Affair” didn’t have much of a future if the focus stayed squarely on two people skulking around to engage in pay-cable-worthy trysts. That said, pivoting to the murder in such a direct way by charging one of the principals with the crime risks elevating that aspect of the show at the expense of others, while reminding us what a delicate high-wire act these premium serials are to keep on track.

None of that undermines what series creators Sarah Treem (who wrote the finale) and Hagai Levi have conjured, but it does flash a warning sign ahead of season two – especially, fairly or not, after “Homeland” started with such promise before veering off course in its second and third seasons, clawing its way back in the fourth.

“Everyone has one book in them,” Noah’s father-in-law told him earlier in the season. “Almost nobody has two.”

“The Affair” clearly had one great, twisty season in it, and let’s be thankful for that. But the unwanted question left dangling by Sunday’s cliffhanger — beyond whether Noah really committed murder by car — is what the show itself has left in the tank for an encore.