Saying that it will prompt important conversations is perhaps not the most scintillating way to describe a TV show; that formulation implies an eat-your-vegetable dryness, or a story saddled with too much lumpy sincerity and not enough engaging momentum.

“13 Reasons Why” is undoubtedly sincere, but it’s also, in many important ways, creatively successful: It uses some of TV’s most popular forms and accessible strategies—the love triangle, the coming-of-age story, the murder mystery and the grounded high school drama—to pull viewers into a suspenseful tale that will keep most of them engaged until the final scene fades out.

The main conceit of the series is explained in the opening minutes: Hannah Baker (Katherine Langford) has killed herself, and the drama’s narration comes from audiotapes she recorded before her death. There are 13 people she thinks share a portion of the blame, and each episode concerns another character who could have helped her more, or harmed her in some way. Of course, she blames herself too — more than she should — but one of the things “13 Reasons” understands well is that apportioning responsibility after a tragedy is a messy, ambiguous project that never really ends.

Langford and Dylan Minnette give career-making performances as the two central characters, Hannah and Clay, who meet in their sophomore year of high school and, recognizing each other as shy, wry outsiders, create a formidable but complicated bond. There is not one false note or even the slightest attempt at manipulation from either actor; the honesty and transparency of their work is frequently jaw-dropping.

The darkness that enters the lives of Hannah, Clay and their friends and classmates is constantly interwoven with the natural resilience and questioning optimism of adolescence, until harder and sadder qualities creep into their eyes. Present-day scenes are interwoven with Hannah-narrated moments from the past, and “13 Reasons” shines when limning the small and large ways in which friendships come to life; the casual ways in which abuse and cruelties are inflicted on Hannah and other young women are also expertly depicted. The tone of the show is not uniformly tragic (though truthfully, it could be a bit more varied, given how tough things get by midway through the season), but Minnette and Langford handle everything that is thrown their way — from comedy to romance to wrenching pain — with impressive grace and commitment. Several members of the cast playing high school characters do similarly specific and raw work (Alisha Boe and Miles Heizer deserve particular praise).

As it progresses through the build-up to the tragedy and the complicated wreckage of its aftermath, “13 Reasons Why” wisely humanizes and contextualizes grief, depression, suicide, and the aftereffects of sexual assault through characters and scenarios that viewers will be unlikely to forget. It’s hard to think about anything else, frankly, once you’ve finished the season. “13 Reasons Why” offers a great deal of food for thought about the kind of individual passivity and group denial that give protection to predators and enablers, and sap hope and nascent joy from those with little power and status. It’s also really funny and sweet at times, and it has a killer soundtrack.

All in all, “13 Reasons Why” does an exceptional job of depicting the intense emotions — and formidable social pressures — of adolescence, without condescending to any viewers, whatever their age. When it comes right down to it, this is simply essential viewing.

Of course, not everyone will be able to engage with some of the subject matter on display. But adult and teen viewers who are able to grapple with show’s most difficult themes should try to power past its uneven and frustrating moments. Not just because of the importance of the issues “13 Reasons” takes on, but because when the storytelling works — and it often does — this show is exceptional.

In the 13 episodes, all of which were screened for critics, there are some very repetitive elements, and some mysteries and revelations are oversold. But this is not a show that can be summed up neatly or given one easily-arrived-at blanket assessment. The lows are low, but the highs are very high, and truly affecting.

“13 Reasons” examines the ways in which adults and school officials turn a blind eye to many kinds of bullying and the worst excesses of jock-bro culture, and that is a laudable goal, but at times, it’s given a shaky execution. If there’s one thing “13 Reasons” could use less of, it’s scenes of parents and teachers being entirely (or willfully) clueless about the toxic behaviors and attitudes that percolate right under their noses; conversations in which oblivious or disinterested adults question uncommunicative and evasive teens quickly grow tiresome.

In general, “13 Reasons” criminally underuses most of the actors playing adults; the main exception is Kate Walsh, who does career-best work as Hannah’s grief-stricken mother. Her character is a ferocious and charismatic open wound, and it’s impossible to look away from her and her quest for answers (the tapes secretly circulate among the kids who are mentioned on them; Hannah didn’t leave a suicide note for her stunned parents).

The show gets progressively more challenging as the season works its way through the tapes delineating Hannah’s decline, but most of what’s on offer comes wrapped up in the standard trappings of teen drama: There’s a big dance, a few raging keggers, a number of tender kisses, some brutally clique-y behavior, and truckloads of secrets and betrayals. One thing that hampers “13 Reasons” is that its attempts to blend amped-up, soapy melodrama and naturalistic, character-focused storytelling don’t always work. From a mechanical perspective, it’s understandable that the drama latches on to a lawsuit that the Baker family files against the school, but “13 Reasons” is less convincing and nuanced when it tries to morph into something that could conceivably be called “How to Get Away with Suicide.”

The drama does have a reasonable amount of forward momentum a good deal of the time, but as Hannah’s story gains urgency, a number of predictable subplots and one-dimensional characters should have been excised. A leaner and more focused version of this show would only have helped it achieve its laudable goals. As it is, one cryptic character whom Clay calls “unhelpful Yoda” does begin to grate over time, attempts to delay certain revelations become cumbersome, and emotionally punishing installments that approach or exceed 60-minute running times can start to feel draining.

Most effective, aside from Hannah’s believable confusion and distress, are depictions of adolescents performing superficial, upbeat versions of themselves to keep adults off their backs, as well as “13 Reason’s” examples of the ways in which the expectations of a competitive culture infused with toxic masculinity drive a number of the young male characters to the brink (and beyond). The way young women absorb the messages of that culture and, in some cases, act on its skewed assumptions in ways that injure themselves and each other is sobering, to say the least.

How can adults tell when the secrets teenagers are hiding are devastating or relatively benign? When do a frustrated teenager’s attempts to deploy healthy skepticism and reasonable detachment slide into depression, and how can a family member or friend spot the difference? How can young men and women — including LGBTQ youth — be true to who they are without fearing the most vicious attitudes of their peers and the community at large? None of these questions get answers in “13 Reasons Why” — but the show is likely to provoke necessary debates about all those things.

Clay spends much of this season with headphones clamped on his head, listening to Hannah tell her story. Like him, we could all stand to listen — and learn.