Chris Hemsworth returns as the God of Thunder for the third installment in Marvel's Norse saga, leading a cast that includes Cate Blanchett, Jeff Goldblum and Mark Ruffalo.

Ragnarök, a prophesied catastrophe in Norse legend, is apparently some kind of a big deal, even by superhero standards. Mainly, though, it's a handy excuse for the latest edition of Marvel-branded sensory overload. One of the most surprising things about Thor: Ragnarok is that it forgoes the umlaut in the title — that winking diacritical mark would have been a nifty signal of the movie's tongue-in-cheek attitude toward its mythology, a comic stance that makes Thor's third outing his breeziest by far.

With Taika Waititi at the helm, the clash-of-worlds CGI extravaganza blasts free of the previous installment's leaden Dark World. Giant fire monsters in stygian underworlds notwithstanding, even the story's central bad guys are silly fun, hammed to the hilt by Cate Blanchett and Jeff Goldblum.

The relatively laidback angle on all the murderous spree-ing gives Chris Hemsworth a chance to find the comic groove beneath the title character's beefcake godliness. He does it expertly, and the self-mocking humor is all the more welcome given Thor's essential blandness. Even Anthony Hopkins' high-ground patriarch feels a tad looser, while Tom Hiddleston offers more of the seething sarcasm that makes Loki, with his ever-shifting allegiances, the best thing to happen to bad hair in the new millennium.

If the antic chords of "See? We don't take ourselves too seriously!" are at times hammered home too insistently, the movie is engaging enough to hold the attention of even those uninitiated in the lore of the Nine Realms. At any rate, as it arrives poised for a megalithic box-office haul, it might be helpful to keep in mind the advice offered by one character: "You cannot stop Ragnarok. Why fight it?"

Besides its assortment of new characters, both live-action and digital, the film indulges in the kind of Marvel Universe crossover storyline that thrills fangirls and their brethren and leaves the rest of us guessing at the degrees of separation. The screenplay, credited to screenwriters Eric Pearson, Craig Kyle and Christopher L. Yost, works to catch us up, to a point, with minimal dialogue clunkiness. Doctor Strange makes an appearance, Tony Stark gets a shout-out, and another of Thor's fellow Avengers plays a pivotal role. But the emphasis is on character dynamics over fantasy-world symbolism — heck, even the usually uncommunicative Hulk opens up.

Waititi's interest in intimate stories was evident in Hunt for the Wilderpeople, but it's the knack for dry comedy that he brought to the mockumentary What We Do in the Shadows that shapes the new Thor. He sets the party-on tone in the movie's first, jokey moments. Soon, with a jolt of Led Zeppelin's 47-year-old "Immigrant Song" fitting the action like a custom-made gauntlet, he brings majestic spectacle down to rock 'n' roll showtime.

Returning to his native Asgard after escaping imprisonment, Thor is drawn back into the cosmic sibling rivalry between him and the devious shape-shifter Loki, who's impersonating their father, Odin (Hopkins), after dumping him on the earthly plane. Further competition for Odin's throne arrives in the form of the brothers' long-lost sister, Hela (Blanchett). A Norse terror with a Goth streak who lives up to the title of Goddess of Death, she's been redacted from Asgard's history and isn't happy about it. Once she smooths back her hair and her antler headgear appears, she's capable of laying waste to whole armies single-handedly. While Hela puts a reluctant Skurge (Karl Urban) to work as her henchman, Thor somehow manages to become a prisoner again, this time on the planet Sakaar.

Ruled by Goldblum's disco-campy dictator Grandmaster (an apparent relation of Benicio Del Toro's Marvel character the Collector), Sakaar is home to a gladiatorial contest that will pit Thor against the Hulk — who, in a nice touch, favors love beads and soaks in the hot tub during his non-fighting hours. Another larger-than-life character, Thor's fellow prisoner Korg (built on director Waititi's motion-capture performance), proves a first-rate comic foil. A stone man with a revolutionary calling, he's a ready ally when Thor gathers together a team to save Asgard.

Also on board is a rattled but willing Bruce Banner (Mark Ruffalo, typically soulful), who has just emerged from a long stint in Hulkdom. Valkyrie (Westworld's Tessa Thompson), a hard-drinking warrior and part-time bounty hunter, exchanges bashful glances with Thor when she isn't spewing tough-girl invective and kicking butt. Idris Elba's steadfast Heimdall, sentry of Asgard, wields his indispensable know-how as facilitator of Thor's strategy.

The high-powered visuals, both practical and computer-generated, include familiar elements from the film's predecessors: the halcyon glow of Asgard, the Bifrost's whooshes of world-spanning multicolored light. At times they recall other movies, as in a trash-heap scene's shades of WALL-E and the scavenger lots of The Force Awakens. Least typical of the genre are the intentionally tacky interiors and primary colors of Sakaar's privileged quarters, the setting for some of the movie's better surprises.

There are moments that might bring a viewer back to the day's news: a citizens' uprising, an exodus of refugees. But amid the strife and the battles — on land and sea, in arenas and in the air — it's the loose-limbed laughs that amp the story's comic-book formula. In the evanescent Ragnarok, even the shock of grievous bodily injury evaporates before our eyes. What will linger when the weapons are withdrawn is the knowledge that you've been prepped for the inevitable next chapter.

Production company: Marvel Studios
Distributor: Walt Disney Studios
Cast: Chris Hemsworth, Tom Hiddleston, Cate Blanchett, Idris Elba, Jeff Goldblum, Tessa Thompson, Karl Urban, Mark Ruffalo, Anthony Hopkins, Benedict Cumberbatch, Taika Waititi, Rachel House, Clancy Brown, Tadanobu Asano, Ray Stevenson, Zachary Levi, Sam Neill
Director: Taika Waititi
Screenwriters: Eric Pearson, Craig Kyle, Christopher L. Yost
Producer: Kevin Feige
Executive producers: Louis D'Esposito, Victoria Alonso, Brad Winderbaum, Thomas M. Hammel, Stan Lee
Director of photography: Javier Aguirresarobe
Production designers: Dan Hennah, Ra Vincent
Costume designer: Mayes C. Rubeo
Editors: Joel Negron, Zene Baker
Composer: Mark Mothersbaugh
Visual effects supervisor: Jake Morrison
Casting: Sarah Halley Finn

Rated PG-13, 130 minutes