Here's a recipe for geek gumbo. Put some elves in a Marvel superhero movie. Sci-fi elves from the distant past, led by a badass named Malekith. He's after something called the Aether, which can be used to rule the universe and was supposed to be destroyed way back when. And put some immortal Vikings on distant planets. Have them fight trolls and monsters in a battle of swords and quantum-magic hammers.
That's just a taste of Thor: The Dark World. It's crazy but awesome, like a heavy-metal Lord of the Rings. With wormholes. Our hero and his folk spring from the same mythic sources as J.R.R. Tolkien's hobbits, after all.
Thor (Chris Hemsworth) is trying to restore peace in the Nine Realms that Odin rules over. But order is not in the stars. Planets will align, portals will appear, and dimensions will get all mixed up. It's called the Covergence, and it happens once every 5,000 years. This is how Thor's mortal main squeeze, astrophysicist Jane Foster (Natalie Portman), accidentally finds the Aether. Then Malekith (Christopher Eccleston, under a ton of evil-elf makeup) goes after her so he can snatch the Aether and become ruler of the universe.
Thor must ask his naughty brother Loki (Tom Hiddleston) for help. Hiddleston is as much a trickster as Loki is, making you feel sorry for his character one moment and then turning the tables. In a movie full of great actors, he steals the show.
Though the cast is just right, the movie has way too many screenwriters: five credited and probably more behind the scenes. This sets it up to become a godawful mess. Yet somehow it floats along on its own sheer madness. The big finale is ingenious. It feels like a sendup of showdowns from the last reels of many superhero movies. Such showdowns are often somber, with high body counts and devastated cities. The Dark World's are funny, as when walloping a bad guy sends him to another planet.
But since The Dark World assumes you've been keeping up with the sprawling film-and-TV Avengers universe, you may not recognize some of the comedy. References to ABC's Agents of S.H.I.E.L.D. are dropped without explanation, and there's a cameo by one of Thor's fellow Avengers that will make no sense if The Dark World is your introduction to the story.
If you have kept up with the franchise, The Dark World isn't confusing because all the interplanetary, multidimensional machinations are tidily explained. It's best not to overthink the details, though. Just take it all in and enjoy the ridiculousness.