HBO’s documentary “I Love You, Now Die,” about a young woman who went on trial for allegedly coercing her boyfriend to kill himself over text message, is clear-eyed and thoughtful, and, in two brisk installments, manages not to overstay its welcome. It tells a story that will startle the unfamiliar and, too, provide new angles for those who’d already known about the unfortunate pair of young people at its center. It amplifies Erin Lee Carr’s status as a young documentarian of unusual achievement, and provides an elegant argument for the true-crime genre as something other than its most heavily-publicized, and worst. This film doesn’t seek to convince you it has all the answers. It’s willing simply to ask interesting questions.

In the film’s first half, we learn the case against Michelle Carter, a young woman in Massachusetts who had been sending bizarre texts to Conrad Roy, a boyfriend with whom she shared a relationship almost exclusively over her phone. Her messages, encouraging him to end his life in increasingly fervid terms, were at the center of a manslaughter case that threatened not merely Carter’s freedom but the legal precedent. That there had never been a case like this meant not merely that there was no clarity as to how it would play out but that whatever decision was made might, in our future, define the wild west of digital spaces.

But it’s the second installment, which complicates and mitigates the story, that is truly striking. An Esquire journalist (to whom, if one were to quibble with the film a bit, quite so much time is ceded that it begins to feel far more like his documentary than Carr’s) notes that Carter appears to have felt and acted out an intense and bizarre overidentification with Lea Michele, the “Glee” actress who experienced a wave of public sympathy after the death of her on- and offscreen boyfriend, Cory Monteith. Carter, who is elsewhere alleged to have been a social pariah who may have been suffering from the side effects of SSRIs, aped her role model online, quoting the exact words Michele used to mourn Monteith without attribution, as if grieving her dead boyfriend had transformed her into a superstar.

Carr, whose breakout film, “Mommy Dead and Dearest,” dealt with the now-infamous Blanchard family case of Munchausen syndrome by proxy, is swimming in familiar enough waters, and can be credited with treating Carter’s story as well as Roy’s with equanimity. She doesn’t advocate for Carter’s exoneration or her conviction, but does build out a story that will convince you Carter’s strange and (at times) seemingly indefensible acts might just spawn from a cocktail of social exclusion, psychiatric meds, and identity in the era of celebrity and the social web. These points are made with whispers, not shouts, and all the better: “I Love You, Now Die” demands you lean forward in your seat and pay real attention. It’s an unusually credible and careful entry in its genre, and one devotees and novices alike should check out.

“I Love You, Now Die: The Commonwealth v. Michelle Carter.” HBO. July 9. Two episodes (both screened for review.)

Executive Producer: Sheila Nevins