After a prologue that recalls the ancient battles between the heroic Asgardians and an evil race known as the Dark Elves, Thor (Chris Hemsworth) is reluctantly preparing to succeed his impatient father, Odin (Anthony Hopkins), on the throne of Asgard.

But then, after Thor's two-year absence from Earth, his heartbroken girlfriend, feisty astrophysicist Jane Foster (Natalie Portman), stumbles upon a vortex that marks the boundary between Realms and she becomes infected by the Aether (a.k.a. a gaseous cosmic substance of infinite destruction), making her the target of the Dark Elves' ruler, megalomaniacal Melekith (Christopher Eccleston). Since detonating the Aether during the Convergence (a.k.a. an astronomical alignment) could plunge Earth and the additional eight Realms into primordial darkness, Thor's coronation must be postponed.

Inspired by Norse mythology and a story by Don Payne and Robert Rodat, it's scripted by Christopher Yost, Christopher Markus and Stephen McFeely, and aptly helmed by TV director Alan Taylor ("Game of Thrones," "Rome," "The Sopranos"). This sequel is darker yet obviously derivative, borrowing from "Star Wars" prequels, "TRON," "Prometheus" and "Man of Steel." Production designer Charles Woods and visual effects supervisor Jake Morrison's most impressive sequences include shape-shifting, the assault on Odin's palace, a striking mass funeral and the climactic battle in London.

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After racing cars in "Rush," Australia's hunky Hemsworth swaggers confidently in the hammer-wielding thunder god's cape and armor, but Portman's talents seem wasted as his romantic interest. In support, Kat Dennings supplies comic relief as Jane's spunky, sarcastic colleague Darcy and Stellan Skarsgard as naked Dr. Erik Selvig, along with Tom Hiddleston as Thor's sneering, trickster brother Loki, Rene Russo as Odin's Queen Frigga and Idris Elba as Asgard's ever-vigilant Heimdall. Marvel's Stan Lee does a cameo, as does another costumed crusader.

On the Granger Movie Gauge of 1 to 10, "Thor: The Dark World" is a stolidly amusing superhero 7, a visual effects showcase. Be sure to stay for two mid-credits/post-credits teasers, heralding 2014's "Captain America: The Winter Soldier" and "Guardians of the Galaxy" and 2015's "The Avengers: Age of Ultron."