Luke David Blumm as Donn Fendler in “Lost on a Mountain in Maine.” Courtesy of Blue Fox Entertainment

Almost everyone who grew up in Maine has read “Lost on a Mountain in Maine.”

Donn Fendler’s tale of being a 12-year-old boy who gets separated from his family on a 1939 Mount Katahdin hike only to reappear an astonishing nine days later some 80 miles from where he left the perilous wilderness trail is the stuff of innumerable Mainers’ book reports. You probably have a paperback copy somewhere.

Now “Lost on a Mountain in Maine” has become a major movie, with the young Fendler (Luke David Blumm) and his adventure of improbable survival in the then-uncharted (and now still not that charted) Piscataquis County woods brought to life by director Andrew Boodhoo Kightlinger and producing help by none other than Sylvester Stallone.

As with any Maine-centric movie, especially one so beloved here in the state, there’s plenty to unpack.

Sadly, the film’s Maine isn’t Maine.

Not to be provincial right off the bat, but it seems more than a little like a slap that this quintessentially Maine story was filmed in New York. Blame Maine’s continued refusal to lure major movie and TV production with the sort of tax incentives other states lure otherwise Maine-set sets out of state.

Still, this is “Lost on a Mountain in Maine,” people. We get a few sweeping aerial shots of the actual majestic Katahdin, but then it’s a case of “a tree is a tree” for the young Donn to get lost in. (It has to be said that, while the real-life Fendler maintained his Maine ties throughout his life, his family was from Rye, New York.)

‘Lost on a Mountain’ isn’t entirely from-away, though.

The film’s non-Stallone producers, Ryan Cook and Derek Desmond, are both from right here in Maine, having teamed up on the 2013 documentary “Finding Donn Fendler,” which tracked down the Maine icon prior to his 2016 death at the age of 90. The pair wanted to shoot in Maine, according to interviews, but it was – wait for it – New York’s generous tax incentives that saw the movie made mainly in the Catskills. Sometimes I hate being right all the time.

In addition, the young Fendler’s never-give-up mother Ruth is played by Caitlin FitzGerald, who brings a steely but welcoming presence to what could have been a pretty thankless “mom is worried” role. A native of Camden, you might know FitzGerald from a varied and successful movie and TV career, including stints on “Station Eleven,” “Succession,” “Masters of Sex” and the gloriously titled film “The Man Who Killed Hitler and Then the Bigfoot.” FitzGerald also played a pivotal role in “Rectify,” which is simply one of the greatest shows in television history that absolutely nobody watched.

FitzGerald’s best scene comes when she, stifled by the meager search party’s lack of progress, whips out the Maine phone book and starts calling everyone from then-Maine Gov. Barrows to local mills and paper companies to the New York Times for publicity and volunteers. She’s so successful that, by the time she calls the Bangor Daily News, they ask her if she’s the mother of that Donn Fendler everyone’s talking about.

Camden native Caitlin FitzGerald and actor Paul Sparks as Fendler’s parents. Courtesy of Blue Fox Entertainment

Luke David Blumm is very good as Donn Fendler.

Casting a kid is tough. Casting a modern child actor in a period piece is tougher. There’s a need for an actor to project that he’s from a time and place removed from us, and Blumm does that. Maybe he’s just got a 1939 face. (Although it’s understandable that the young actor wasn’t starved to look like credit sequence news photos of the actual Fendler, who emerged from his ordeal emaciated and covered in scrapes and bug bites.)

The emotional crux of the film comes from Donn’s contentious relationship with his stern father (Paul Sparks of “Boardwalk Empire” and “House of Cards”). The elder Fendler is portrayed as a hard-working, emotionally reserved dad, constantly snapping off bad economic and looming World War II news from the family car’s radio when not constantly leaving home for work. Meanwhile, Blumm’s headstrong Donn simmers in resentment at his father’s absence – whether he’s on the road or at home.

After the getting lost part of “Lost on a Mountain in Maine” kicks in (not a spoiler), Blumm makes the resulting separation from his oppressive dad feel like freedom at first. Singing battle hymns while thrashing through mountain streams, young Donn first relishes the boy’s adventure of it all – at least until northern Maine’s bugs, leeches and impossibly sharp tree branches intermittently ruin his fun.

Regaled with a story of the Penobscot bird spirit Pamola in a scary campfire story by the family’s guide (Ethan Slater), Donn gradually succumbs to the realization that he’s going to have to fight for his own survival. The ensuing hunger, freezing rains and damnably ubiquitous black flies and mosquitoes gradually sap his strength until his conception of the imposing Pamola becomes his nemesis and – in the film’s most affecting scene – his imaginary protector.

Blumm manages to act like a real kid, which is harder than it looks. Talking out loud in snatches of songs and wisecracks, this Fendler isn’t – in deference to Stallone’s Balboa Productions – a Rambo. His scrabbling survival tactics come in fits and realistic, childlike starts. Upon finding a long-abandoned cave shelter midway through his journey, Donn (in his boxers, thanks to some impenetrable Maine thorn bushes) calls out, “Sorry I don’t have any pants on! It’s a long story.”

But the film undercuts its own drama at every turn.

Director Kightlinger and screenwriter Luke Paradise employ a maddening pattern of distracting storytelling techniques. Never comfortable going full wilderness survival thriller (perhaps looking to become as family-friendly a keepsake as Fendler’s book), the film cuts away from Donn’s compelling travails every time they threaten to get too intense.

Now nobody’s expecting a PG-rated adaptation of a beloved kids’ book to go full-on body horror (as in the unflinchingly gruesome 2017 Daniel Radcliffe true survival tale “Jungle”). But apart from a little toenail violence and the occasional leech attack, the film never quite brings home just how much danger Donn Fendler is actually in.

The onscreen count of the days whiz by (even skipping a few), with Blumm ably getting more and more bug-bit and scarred. But Kightlinger immediately then cuts to archival footage of people involved in Fendler’s real rescue (rangers, searchers, Donn’s sensitive and guilt-ridden brother Ryan), explaining their roles in things we’d much rather watch being dramatized. The real-life adult Ryan explains how spotting a dead bird during the search brought home the devastating certainty that his twin brother was dead – right as we watch the young Ryan (Griffin Wallace Henkel) find a dead bird and imagine Donn is dead. It saps the heck out of the drama, as do some unnecessary dream sequences.

Also, Kightlinger needs to cool it with the incessant slo-mo, which brings a cliché melodrama to scenes that could stand just fine on their own.

Overall though, Fendler’s unlikely tale of survival is worth getting lost in.

Apart from the low-key excellent Blumm (and some affecting stiff-upper-lip work from Sparks and FitzGerald), “Lost on a Mountain in Maine” becomes surprisingly effective emotionally as a story of father-son friction and eventual cathartic bonding. (FitzGerald’s good but stuck as the idealized mom figure too often.)

As the filthy and bloodied Donn wavers on the brink of giving up, his imagined conversations with his father are hard to resist, even if you’re a cynical old movie critic. (Also, I need to call my dad.)

“Lost on a Mountain in Maine” is playing in theaters all over Maine and can be streamed with an Apple TV subscription.