Horror on episodic TV is difficult to pull off for one big reason: Pacing. As the back halves of most “American Horror Story” seasons tend to prove, keeping up a tone of dread over hours and hours of running time is a challenge, and coming up with compelling reasons for the story to keep going is harder still. There’s also the issue of suspension of disbelief: If the spell of the story is broken each time an episode ends, it can be hard to re-immerse.

That last point, at least, is not a problem for “Servant,” a new horror series executive produced by M. Night Shyamalan. While it will be served to Apple TV Plus subscribers on a weekly model and not, initially, available to binge, the mood it conjures is so overwhelming, so claustrophobically creepy, that it’s easy to feel instantly stifled when an episode begins.

Less convincing is the manner by which the story stretches on, and on. The premise, involving a couple (Lauren Ambrose and Toby Kebbell) who, after the loss of their baby son Jericho, pretend he’s still alive. (Her brother, played by Rupert Grint, is in on the ruse but feels as dubious about the whole thing as viewers might.) This seems, at first, like a concession to Ambrose’s character’s obsessive image-consciousness — she’s a local celebrity, a correspondent for the Philadelphia TV news affiliate — but quickly comes to seem like the thing keeping her from fracturing, the dream she needs to be allowed to live in to avoid reality breaking her entirely. In order to tend to the (discomfitingly weird-looking) baby doll they’re raising as a son, Ambrose’s Dorothy and Kebbell’s Sean hire a nanny named Leanne (Nell Tiger Free), a young woman whose extreme obedience and recessiveness lend the show its title and its air of menace disguised as benevolence. It requires complications — less the sort of single twist for which Shyamalan became known early in his career with films like “The Sixth Sense” and “The Village” than a passel of reversals and reveals — in order to explain why Sean remains on board with the pretense that Jericho is alive, especially after developments arise that suggest Leanne may be a kidnapper or worse.

There’s much to admire in “Servant” — for instance, the show’s painterly compositions, if at times underlit, isolate Free’s character in the far background, as if to say that her soft-spoken, perhaps malignant caretaker character has the ability to literally blend into the background. Ambrose, a welcome presence underseen on big-ticket television since the “Six Feet Under” finale in 2005, makes big and risky choices in constructing her character. She combines brittleness with a bitter sense of humor such that our understanding of Dorothy evolves over the series’s run. As we learn more about her and Sean’s marriage (one in which he, a chef, is often physically absent and yet more frequently disengaged), we shift, eventually, from seeing her as the source of tension to someone bearing its brunt.

And yet for all this, and for all that “Servant” is the most watchable show yet in Apple’s vexed rollout, the series’ somewhat loopy pacing is punishing. Leanne seems as the show runs on to represent far less than meets the eye; episode after episode unfolds without her doing much of anything but seeming threatening in her inaction. (We know she’s going to have to do something eventually, but the wait grows less tantalizing than stultifying.) And to get to a new understanding of Dorothy, one has to trudge fairly deep into the series’s run, long after some viewers may have written her off. And Sean’s willingness to keep her in the dark comes to read less as benevolence than a somewhat uninteresting, uncomplicated sort of villainy. Their behavior raises the question of whether these two can have credibly loved one another in the first place — a twist this story can’t bear. If they are content to torment each other and themselves unremittingly — if, in other words, they truly do not care about each other — then why should we? “Servant” is fascinating to look at and, at first, contemplate. But its slithering, reversing structure elides the fact that it must move the plot forward only infinitesimally each episode in order to conserve it, and that this is a shortish feature in the costume of a ten-episode drama. That’s its biggest, and least welcome, twist of all.

TV Review: ‘Servant’

Apple TV Plus. Ten episodes (all screened for review). Running time: 30 MIN.

  • Production: Executive Producers: M. Night Shyamalan, Tony Basgallop, Ashwin Rajan, Jason Blumenthal, Todd Black, Steve Tisch, Taylor Latham.
  • Cast: Lauren Ambrose, Toby Kebbell, Rupert Grint, Nell Tiger Free.