Chris Hemsworth plays the title superhero in "Thor: Ragnarok," coming...

Chris Hemsworth plays the title superhero in "Thor: Ragnarok," coming to theaters on Nov. 3, 2017. Credit: Marvel Studios

PLOT The god of thunder must save his homeland from destruction.

CAST Chris Hemsworth, Cate Blanchett, Mark Ruffalo

RATED PG-13 (battles and some bloodshed)

LENGTH 2:10

BOTTOM LINE A newfound sense of humor livens up one of Marvel’s lesser franchises. (Movie opens on Nov. 3.)

Let comic fans argue over who’s the strongest Avenger. Cinematically, the weakest is surely Thor. Though played by a perfectly cast Chris Hemsworth, who combines Nordic good looks with sly intelligence, the Viking god with the flying hammer remains a fuzzily-defined superhero.

He isn’t a lovable rogue like Iron Man, nor does he represent chivalry and sacrifice like Captain America (both of whom best Thor at the box office). Over two films, Thor has walked an unsteady tightrope between heavy-metal fantasy and winking self-mockery — a superhero persona in limbo.

That ends with “Thor: Ragnarok,” which turns down the Shakespearean pretensions, cranks up the humor and delivers what is essentially an action-comedy with swords and capes. Written by a trio of Marvel television veterans (including Eric Pearson of “Agent Carter”) and directed by the comedic filmmaker Taika Waititi, “Thor: Ragnarok” is all about the deadpan zinger, the gonzo performance, the unexpected pratfall. It’s a close cousin to “Guardians of the Galaxy,” a high-energy lark that occasionally makes time for monsters, battles, bloodletting and spectacular special effects.

“Thor: Ragnarok” is a very busy episode. For starters, the film’s subtitle refers to the destruction of Thor’s mythical-yet-real homeland, Asgard. Part of that involves the evil sister Thor never knew he had, Hela (Cate Blanchett in a black catsuit, Gothic eyeliner and metallic antlers). In a plot detour that takes up most of the movie, Thor is imprisoned on a trash-heap planet, Sakaar, where a cheerful tyrant known as The Grandmaster (a priceless Jeff Goldblum) forces Thor into a gladiator-style battle with his old pal The Hulk (Mark Ruffalo, mostly in green mode).

Regrettably, this newly freewheeling “Thor” has less use for the magnificent Tom Hiddleston as Thor’s backstabbing brother, Loki. Hiddleston is just a little too intense to join the fun; he can transcend genre, but he can’t play pranks on it. In exchange, we get a probable new addition to the franchise, Valkyrie (Tessa Thompson, “Dear White People”). Thompson feels a bit young to play a once-proud warrior now drowning in booze, but she shines in her cool-and-cocky moments.

The key ingredient in “Thor: Ragnarok” is director Waititi, something of a national treasure in his native New Zealand (several of his films have set box-office records there) and a cult item in the United States thanks to his vampire-roommate comedy “What We Do in the Shadows” (2014). Waititi gives himself the role of Korg, an amiable dude whose body is made of rocks. He’s harmless, he says — “unless you’re a pair of scissors.” It’s exactly the kind of wry, dry humor that the soggy “Thor” franchise needed.

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