Little else needs to be said to appreciate the trenchant message in “Under the Banner of Heaven,” as adapted by Dustin Lance Black (who last tackled Mormonism as a staff writer on HBO’s “Big Love”), but the limited series keeps probing the inherent complications of unquestioned piety over its seven lengthy episodes. (The five screened for critics run 63-68 minutes each.) Religion doesn’t always bring about the best in men. Preaching peace and love from the pulpit doesn’t mean practicing either behind closed doors. And while “Under the Banner of Heaven” does a fine job laying out which aspects of Mormonism tend to bear bad apples (as well as which splinter groups actually condone them), its mystery isn’t meant to be astonishing and its significant takeaways should be evident early on — at least to anyone familiar with any era of world history. Related Netflix’s ‘Kaleidoscope’ Unlocks a Watch-In-Any-Order Format for an Intriguing Heist Show Peacock’s ‘Paul T. Goldman’ Is Part ‘The Rehearsal,’ Part ‘Curb,’ and Totally Wild Related Growing Number of Contenders Makes 2023 Best International Feature Race Less Predictable Oscars 2023: Best Sound PredictionsProduced by FX but airing only on Hulu, the series opens in 1984 and centers on Andrew Garfield’s Detective Jeb Pyre. The baby-faced lawman is a husband and father of two young girls, as well as the senior detective in his small-town station. An idyllic night spent playing and praying with his kids is interrupted by a grisly call to service. Two people are dead. The chief is on vacation. When Jeb arrives at the scene of the crime, there’s a cop seated outside, crouched on the front stoop with his head in his hands. What’s inside unsettles anyone who sees it, though the audience’s impression of what happened is left predominantly to the imagination. Director David Mackenzie takes a sensitive approach to match his sensitive subject. Watching Jeb’s reactions, empathizing with his anguish, is what matters, rather than studying the gory remains ourselves. There’s a puddle of blood on the kitchen floor, though it’s only seen in full from two rooms away. Closer inspections of gruesome evidence are fleeting. By the time a red handprint is spotted on the nursery door, it’s clear this case has already left a mark on Jeb.

What follows maintains a gentle nature toward what’s shown and discussed, even as the subject matter gets gnarly. The remote suburb of Salt Lake Valley, Utah doesn’t see a lot of deaths like these, which makes Jeb’s job all the harder. Not only does he have to guide a young, innocent group of officers to assist in the ever-broadening investigation, but he has to keep information from spreading too quickly through the tight-knit Mormon community. The victims’ husband and father, Allen (Billy Howle), who shows up as Jeb is exiting the crime scene, is part of a massive Lafferty family. Locals call them the “Utah Kennedys,” but tracking them down proves difficult. Allen has recently split from the church. Since then, his brothers have moved. Still, he’s heard that “bearded men” have been following his family. As generic and desperate as that claim may sound, Jeb hears Allen out — partly because there really aren’t that many bearded men in town, but more so because he’s desperate for a suspect who’s not involved in his church. It’s only when Allen starts asking them to look into the Mormon faithful that Jeb snaps. Such an inquiry doesn’t just go against the good detective’s instincts, it threatens his way of life. Could a member of the LDS faithful really do something this heinous? Could someone he calls “brother” or “sister” betray the values instilled by such intimate communal bonds? Could those very values be part of what pushes certain members to harm people? Michelle Faye / FX Even if you haven’t read John Krakauer’s 2003 book or otherwise know how this true story plays out, the answer to each of those questions is the same: “No shit.” “Under the Banner of Heaven” doesn’t pretend otherwise — its suspect list is narrowed to the expansive Lafferty clan rather quickly — but Jeb himself proves to be an odd fit. In various scenes, he’s so distraught by his findings that he cries, falls to his knees, and dry heaves behind his desk. Garfield sells Jeb’s joyful devotion to the LDS Church with an earnestness befitting a simple man with simple wants, but it’s hard to pair the detective’s determined pursuit of truth with the parishioner’s complete lack of curiosity in regard to his own faith. The questions brought forth by the case aren’t so extreme he shouldn’t have considered them years earlier.

Setting Jeb’s individual authenticity aside, the case and its implications carry irrefutable (if obvious) relevance to modern America. Issues of fundamentalism and secularism are prominent. Though likely to be labeled as such by some, “Under the Banner of Heaven” isn’t anti-Mormon or anti-religion; it’s pro-investigation. Just as Jeb’s dogged pursuit of the killer matches his personal quest for spiritual peace, the series calls on viewers to interrogate their own convictions, instead of blindly accepting what they’re told. LDS parishioners are often instructed to put difficult questions “on a shelf” — in other words, they’re told to ignore them until they find an answer later in life, or they eventually give up and trust the Church knows better than they do. The reasoning, as it typically goes, is that accepting the unknowable is part of faith itself. Discerning what needs to be known from what can’t be known and what certain people don’t want to be known makes “Under the Banner of Heaven” thematically compelling. Beliefs grounded in self-serving ideologies are running rampant. Lines between church and state continue to erode. Plenty of ongoing American crises can be traced back to foundational flaws that people refuse to rectify. Similar to Krakauer’s book, the show draws parallels between the case and church history to illustrate these points, though it can get a little lost in its own tutelage. Jeb’s partner Bill Taba (Gil Biringham), a former Las Vegas cop who doesn’t ascribe to LDS gospel, often serves as an audience proxy; at one point, he even tells a suspect, “As the only non-member here, I’m in need of an education,” but that line may as well lead in every flashback to Joseph Smith, Brigham Young, and more bluntly incorporated bits of Mormon background. Fitting in enough context so that unfamiliar audiences understand how the past and present connect can create disjointed, cumbersome episodes. Every entry is 10 minutes too long, and none of the centuries-old sequences are nearly as compelling as the active case from 1984. With so many characters — there are a dozen Laffertys alone, plus new friends and followers added every hour — it can be hard to keep track, and the series adds even more time (via quick flashes of memory, exposition, and more) to help you remember who’s who. Female persecution is a staple of the church noted early and often, though room isn’t made for the cast’s women to establish comparable interiority to their husbands and fathers. All these flaws may prove trivial if the series’ ideas grab you. But all the apparent and admirable love put into this sprawling adaptation may only boil down to one or two simple truths. Faith, in the wrong hands, can embolden dangerous men. If you don’t know that by now, “Under the Banner of Heaven” will slowly, painstakingly make its case.

Grade: B-

“Under the Banner of Heaven” premieres its first two episodes Thursday, April 28 on Hulu. New episodes will be released weekly. Sign Up: Stay on top of the latest breaking film and TV news! Sign up for our Email Newsletters here.