You can't accuse Thor: Ragnarok of playing it safe. The third film about Marvel's superhero based on the Norse god of thunder shakes things up drastically, taking the series in a more colorful, more fantastic and more comedic direction.

But you can accuse it of leaving some members of its potential audience behind. To fully appreciate or even understand Ragnarok, it's not enough to have just seen the first two movies. You also need to have seen both Avengers films, and probably Doctor Strange. If you aren't neck-deep in the Marvel Cinematic Universe already, then this movie isn't for you.

The changes are for the better, though, and if you are up for a fantastic ride through Marvel's sci-fi worlds, there is a lot of fun to be had here at the end of the world.

While trying to prevent his visions of Ragnarok (an apocalyptic series of events in Norse mythology) from coming to pass, Thor (Chris Hemsworth) ends up going toe-to-toe with a sister he never knew he had -- the goddess of death, Hela (Cate Blanchett). As seems to always be the case, he finds himself teaming up with his brother Loki (Tom Hiddleston), who -- surprise! -- is not completely trustworthy.

Most of the movie isn't spent with Hela, though. It's spent on the garbage planet Sakaar, where Thor is captured by a former Valkyrie (Tessa Thompson), an elite soldier from Thor's home, Asgard. On Sakaar, the flamboyant Grandmaster (Jeff Goldblum) forces Thor to fight a gladiator match against the Hulk (Mark Ruffalo), who hasn't returned to his human form, Bruce Banner, since the events of Avengers: Age of Ultron.

Sound like a lot? It is. Ragnarok is constantly at risk of trying to do too much in too short a time, and if you haven't been keeping up with the series, some major plot points may zoom past you. Reading Marvel comics themselves isn't a requirement (though readers of Planet Hulk might be happy to see elements of that story on screen here), but you do need prior movie knowledge.

Another recent Marvel movie, Guardians of the Galaxy Vol. 2, makes connections to the larger MCU without relying on it. Even Spider-Man Homecoming, which does depend on the events of an earlier film (Captain America: Civil War) catches viewers up efficiently. 

Thor: Ragnarok does not. It leans heavily on what came before.

This is a bit odd considering how quickly the movie is willing to shed remnants of its own franchise. Most of the characters from the first two Thor films, including all of the Earth-born ones, are completely MIA. Even Thor's love interest, Jane, is brushed aside with a single line of dialogue explaining that she and Thor have broken up. (A line delivered by glorified extras, no less.)

As it moves at its breakneck pace, though, Ragnarok is a blast. It opens with a battle against fire demons that looks like it could have been the cover of an intense heavy metal album. Led Zeppelin plays one minute, but you'll catch a whiff of "Pure Imagination" from Willy Wonka & the Chocolate Factory the next. There are jokes about guns (in which Texas plays a role) and Shake Weights There are big fights and flashy action sequences and fun character interactions and many, many jokes. (PSA to parents, more of these jokes involve sexual themes than those in previous Marvel movies.)

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The humor stands out. One-liners aren't as much in the spotlight as they are in Guardians of the Galaxy, but Ragnarok is not as deathly-serious as its predecessors could sometimes be, which works in its favor. They were Shakespearean and grim, laughing at themselves only occasionally. In the original Thor, the god of thunder was himself the punchline of most jokes, his lack of understanding about humanity being played for laughs. While Thor still has moments of laugh-worthy stupidity, he's more willing to make quips than he once was.

And yet the stakes are still high. The end of the world is nigh, after all, and Ragnarok takes that threat -- and its repercussions -- seriously enough to make you worried about the state of this universe moving forward. Because the next time we'll see Thor will be in 2018's Avengers: Infinity War, and it's hard to imagine every hero coming out of that one unscathed.

For now, though, this is the most fun it has ever been to hang out with Thor.

THOR: RAGNAROK (B-)

PG-13 (for intense sequences of sci-fi violence and action, and brief suggestive material). 130 minutes. In wide release.

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