When Marvel released “Thor” in 2011, I doubt that most of us on this side of the screen realized how important the adventures of the Thunder God would become to big-screen Marvel.

I liked “Thor” really pretty well. Maybe not as much as “Iron Man” or “Captain America,” but I thought the movie did a very good job of introducing the more fantastic elements of the Marvel Universe to the moviegoing audience. With “Thor” a success, how far behind could “Dr. Strange” or the cosmic Marvel stories or even the horror-tinged reaches of the Marvel universe be?

As it turns out, Marvel and director James Gunn are making the “Star Wars”-ian “Guardians of the Galaxy” now, for release next year. There’s a connection between “Thor” – spoilers ahead, I’ll warn you before – and “GOTG” but after duty in “The Avengers,” the Asgardian god of thunder returns in “Thor: The Dark World,” which stakes out, even more than the original, the more mystical, more space-bound corner of Marvel.

I won’t go very deep into the plot. Suffice it to say that Thor (Chris Hemsworth) returns to face an enemy (former Doctor Christopher Eccleston) intent on avenging himself on Odin (Anthony Hopkins) and Asgard and recapturing the Aether, force of cosmic power not unlike the Tesseract, the mystical Cosmic Cube from “Captain America” and “The Avengers.”

The movie skips from Asgard to London, where Thor is reunited with Jane Foster (Natalie Portman) and her crew, and to other stops among the Nine Realms.

Director Alan Taylor (“Game of Thrones”) and the screenwriters make this sequel a far grittier – literally and figuratively – story than the original. Asgard has texture and the Dark World itself is a nightmarish landscape. London is the steely blue/gray we’re familiar with in modern-day TV outings like “Sherlock.”

The action is thrilling and the realm-skipping action shows every penny of the production budget.

Hemsworth is so at ease as Thor it’s fun to imagine him  playing the part for years to come. Likewise, Tom Hiddleston is such a welcome presence as Thor’s trickster brother Loki that I hope he becomes omnipresent in movies.

“Thor: The Dark World” could feel like just another step in setting up the decade-long Marvel movie plotline, as I talked about in this recent entry. But it doesn’t. It never feels perfunctory. It’s a grand, thrilling adventure in its own right.

Random observations:

Spoiler this line only: What I reported the other day about the two end credits sequences was correct. The first featured Benecio Del Toro as the Collector and sets the stage for “GOTG.” It’s a fun if oddball scene, directed by “GOTG” director James Gunn. It’ll be interesting to see how “GOTG” comes out next year.

Obviously Chris Hemsworth’s contract calls for a minimum of one shirtless scene per “Thor” movie.

Hiddleston gets to play more vulnerable and more multifaceted here than in “Thor” of “The Avengers.” It’s great and unsettling at the same time.

No spoilers here, but I loved the cameo. That’s the advantage of a shared big-screen universe.

‘Thor: The Dark World” marks the eighth movie in the official big-screen Marvel universe. Eighth.