J.R.R. Tolkien once said that "believable fairy-stories must be intensely practical. You must have a map, no matter how rough." But in Peter Jackson’s new and final Hobbit film, The Hobbit: The Battle of the Five Armies, which opened Wednesday, there is no map. There’s not even a plan. We veer far not just from Middle-earth, but from all plausibility.

But you can’t blame Tolkien for this. Jackson got us here; he’s the one who must be stopped.

It’s not that I’m anti-Peter Jackson. I followed the Lord of the Rings trilogy through Middle-earth like a drooling orc-puppy. I like my fantasy to be exciting, and to take me places I have never been to, and for its protagonists to do cool, heroic stuff. Jackson’s first Tolkien threesome hit all these sweet spots, and made me care about his characters to boot; they were well-rounded people (and hobbits, and elves, and dwarves) whose exploits and feats were still believable.

That’s simply not the case with his Hobbit movies.

Wait, you say. This is fantasy. It’s a story about dwarves, elves, dragons, wizards, pipe weed, and magic rings. Anything can happen, right? Well, not quite. For fantasy to work, it has to be based on reality. And ultimately, these Hobbit films do not feel real.

The issues go back to An Unexpected Journey, the opening film of the trilogy. This film was widely derided for its gratuitous use of action sequences—and rightfully so. There’s wizard Radagast (Sylvester McCoy) driving a rabbit-pulled sled in order to distract orcs so Gandalf (Ian McKellen), the Dwarves, and Bilbo (Martin Freeman) can escape them. There’s the physics-bending episode in the Goblin King’s cave, in which our adventurers are chased along a series of computer-generated catwalks; their fight with the goblins is a horrific ballet of Three Stooges-caliber pratfalls. But when Bilbo tumbled what looked like 350 feet into Gollum’s cave, and survived? That was the moment when I knew that the film was truly a goner.

In film two, The Desolation of Smaug, many of us grimaced at a river-and-barrel sequence more at home in a Disney theme park than a Tolkien movie. The dwarves’ absurd attempt to create a tidal wave of hot gold to pour over an irate Smaug the Dragon was the molten-metal topping to the hubris that is Mount Jackson. Not to mention the silly elf-dwarf romance—which Peter Jackson recently admitted was a "cold-blooded decision" to appeal to "a lot of young girls seeing this film."

You can’t fault Jackson for his physical world-building. The attention to detail—every set, every special effect, every prop and suit of armor and ruined town, every last smoldering candlestick and dragon scale—is unparalleled. Middle-earth feels real. But in these Hobbit movies, the more important thing to get right is situational realism: How the plot turns, what the characters do, if they move through space in a believable way. All this is thrown out the door. The sincerity of Thorin and Bilbo's struggles is completely undermined by the story’s blanket disregard for physics, logic, and credibility. Gone into the ether is Tolkien’s gentle, thoughtful, and more plausible children’s tale.

This isn’t the first time Jackson has been unable to exercise restraint. Think of his early films: Bad Taste; Meet the Feebles; Braindead. He’s always loved blood and guts (and slime) and cheap jokes.

There were even tinges of it in his Rings trilogy. The Two Towers features that unfortunate "Legolas surfing on his shield" incident, and Gimli’s jokes about "the consistency of squirrel droppings" and a orc "twitching because he's got my axe in his nervous system" had no place in Tolkien's world. In The Return of the King, Jackson globs on the garish green ghoul effects—he especially loves that otherworldly misty effect—and can’t resist having Aragorn, Gimli, and Legolas running from a cascade of skulls. That all seemed forgivable, though, given the gravitas of everything else in the first trilogy.

But now The Battle of the Five Armies is no different. He invents giant burrowing worms whose tunnels the invading orcs march through. Trolls have catapults mounted on their backs. Hunky archer/he-man Bard (Luke Evans) jumps in a cart careening down a staircase to kill a troll. Like a deranged killer in a Friday the 13th movie, orc villain Azog waits under the ice to ambush head dwarf Thorin (Richard Armitage). Super-elf Legolas (Orlando Bloom) hitches a ride on a giant flying bat—and another on a plain old giant troll, his sword jammed into the creature’s brain like a joystick to steer it. And is that Wile E. Coyote making a gravity-defying jog up a stone bridge that crumbles beneath his feet? No, wait, that’s Legolas again.

Yes, Jackson is a great action director, and his heroes have always seemed skilled (and extremely lucky) in battle. But in Five Armies, the computer-generated combat reaches new levels of kinetic fury. One particular fight involving Gandalf, Saruman (Christopher Lee), Elrond (Hugo Weaving), Galadriel (Cate Blanchett), and the Necromancer may as well be from Mortal Kombat for all its gymnastics, combos, and finishers. By the end, every major (and minor) character has clashed with some arch-foe or another, and it’s wearying.

In Tolkien’s original book, Bilbo Baggins describes how he feels after wearing the Ring of Power: "thin, sort of stretched, like butter scraped over too much bread." That same feeling, sadly, applies to what’s happened to a simple story of a hobbit's journey of self-discovery.

Like General Sherman’s final campaign through the South, this will be Peter Jackson's last march through Middle-earth. "Without the cooperation of the Tolkien estate, there can’t be more films," Jackson said at a press conference after The Battle of the Five Armies' world premiere in London. At the moment, Tolkien’s heirs don’t seem eager to sell the movie rights to any of his other works. Like the Elves who depart Middle-earth for Valinor, it seems that Jackson’s hold over Tolkien’s will someday fade.

But meanwhile, he’s surely preparing his extra-extended dance mix version of Five Armies for DVD, adding even more gore and hero moves. Before he does, let’s hope some generous fan makes a cut of this entire Hobbit trilogy that restores it to sanity. And believability.