I always say that superhero movies are defined by their villains, and “Thor: The Dark World” has a lulu in Tom Hiddleston‘s Loki, who was not as vanquished at the end of “The Avengers” as we thought.  Thank goodness. Loki, the eternal trickster of Norse myth, is imprisoned by his father, Odin (Anthony Hopkins) at the beginning of the story.  But a once-in-5000-years celestial line-up brings on an attack by the Dark Elves, let by ninth Dr. Who Christopher Eccleston and “Oz’s” Adewale Akinnuoye-Agbaje, and soon Loki is freed.  Chris Hemsworth continues to bring all the requisite charisma and some welcome wit to the heroic Thor and Hopkins is nicely magisterial as the one-eyed Odin, but it is Hiddleston who is clearly having a blast as a god who lives for chaos and brings a jolt of pure devilish pleasure to every scene he is in.

That is particularly welcome because all those scenes in Asgard can get rather ponderous.  And the movie begins inauspiciously with some Tolkein-ian mumbo-jumbo about the battle with the Dark Elves and some icky black smokey-stuff that has some important power and a bunch of parallel universes.  Who cares — let’s get to the good stuff already.

Meanwhile, back on earth, the world’s most beautiful astrophysicist, Jane Foster (Natalie Portman), is wondering whether her super-boyfriend is ever going to call.   Her colleague, Dr. Erik Selvig (Stellan Skarsgård) is running around with his pants off, and sometimes with the rest of his clothes off, too, and her intern (Kat Dennings) and her intern’s intern are helping her investigate some very strange gravitational anomalies.  All of this, except for the boyfriend part, relates to this once in a quinti-millennium astrological line-up that opens up portals or melts the boundaries or some crazy thing that lets the parallel universes seep into each other.  Jane gets slimed by the black smokey stuff and Thor whisks her away to Asgard.  I wish I could say it was a side effect of the smoke that has her more concerned about the significance of meeting her boyfriend’s parents than a scientific inquiry into the nature of the home of the Norse gods, or understanding the life-threatening nature of the Dark Elves’ smoke.   But no.

Pantlessness aside, there are some genuinely funny moments, including a surprise appearance by one of the other Avengers and a mid-battle trip on the subway.  The fight scenes are strong, well staged by “Game of Thrones” director Alan Taylor, and there are some predictably cool special effects.  Rene Russo is fine as Frieda and there are not one but two extra scenes in the credits.  But the reason to see the movie is Loki — he should get his own movie next time around.

Parents should know that the movie includes extended comic-book-style action violence with some graphic images, characters injured and killed, a hand chopped off, fatal stabbing, some strong language, and comic nudity (nothing shown).

Family discussion: How does Thor compare to other superheroes? Did you like the touches of comedy or find them distracting?

If you like this, try: “The Avengers” and the first Thor movie.