(CNN) - By weaving a slow-unfolding mystery throughout its grim first season, "13 Reasons Why" became a much-discussed sensation on Netflix, controversially built around sexual assault and a teenage girl's suicide. The encore, alas, can't replicate that appeal, detouring into courtroom drama in a manner that provides far fewer reasons to watch or binge.
The original concept turned Jay Asher's book into a brilliantly conceived format for a series, drawing on a series of audiotapes -- focusing on different key characters' role in the story -- left behind by Hannah (Katherine Langford) that explained what happened.
Season two picks up months later, and there's still plenty of detail to be unraveled about Hannah's past, as the boy with whom she bonded, Clay (Dylan Minette), continues to seek answers. Other kids, such as Jessica (Alisha Boe), grapple with their experiences, and genuine fear regarding what to say publicly about them at a school where star athlete Bryce (Justin Prentice) remains the smiling face of evil, hiding in plain view.
Yet too much of the narrative shifts to the courthouse, where Hannah's grieving mother (Kate Walsh) -- the main standout among a mostly ineffectual bunch of parents -- is seeking justice for her daughter, while still wrestling with regret, confusion and guilt. Those feelings are only exacerbated by some of the testimony, prompting her to wonder in a later episode, "How can you fix something if you don't know it's broken?"
Although the cast remains strong, the show has sacrificed the momentum associated with season one's structure. And while all the players carry scars to varying degrees, the subplots and unknowns this time -- including anonymous messages and warnings designed to intimidate Clay and his allies -- have ebbed in their allure.
The flashbacks work notably better than the present-day material, which includes the unfortunate creative choice of having Hannah appear to Clay as what amounts to a ghostly vision. While increasing Langford's presence is an understandable goal (she's again terrific), it's a tired device, one that makes the series feel more like a conventional teen soap.
The first season largely avoided those pitfalls, in part by dealing so unflinchingly with the difficult subject matter. That approach also brought criticism about glamorizing teen suicide, which Netflix has addressed with disclaimers taped by the actors and information regarding a website where those who are troubled can seek help.
That's welcome, but other aspects of the drama -- including the combustible mixture of high school and guns -- remain problematic. The finale sums those issues up in a nutshell -- distinguished by powerful moments regarding sexual assault, but simultaneously undermined by more questionable developments. Ultimately, it's not enough to redeem these episodes or spark appetite for more.
The latitude Netflix enjoys means not being locked into stock TV formulas, among them continuing to exploit shows that have exhausted their core material. The streaming service can be forgiven for wanting to sustain a popular franchise, but what made this series special has already been significantly diluted by piling more reasons upon "Reasons."
"13 Reasons Why," Season 2 premieres May 18 on Netflix.