Nigel Cook, International VP of Marvel Studios, spoke at a film convention in Italy and showcased the very first footage seen anywhere of Thor: The Dark World.
Here is a rough translation of the footage:
“In the preview, a voice-over is heard with the oath of the God of Thunder as the new supreme ruler. We see a clash between Thor and the enemy army, in a world that is neither Asgard let alone the Earth. We see Chris Hemsworth wielding his hammer and Tom Hiddleston as Loki first wounded without a helmet, with long, loose hair and then imprisoned; his anger increasingly desperate and irrational. Then there’s a scene later in which he is free again, but still furious.
Against the backdrop of a forest, in the middle of a clearing, among the dust, we in fact face off anthropomorphic creatures, but also a big “gorilla” krosan tusker: a rather alien fauna varies so, although not extreme in size (there are also some envoys/ambassadors of a people mysterious, with oval face and black eyes, elongated and sunken)
The rest of the images show glimpses of Asgard, with Anthony Hopkins as Odin and Natalie Portman in clothes that seem more like a princess; an Asgardian princess. In between, there are images of an epic battle on horseback, who seems to have left an epic cloak-and-dagger. The threat to the Asgardians is certainly a new alien race pale (now identified as the dark elves).
A black spaceship shaped irregularly looks like a serious threat to Asgard. More sequences show Natalie Portman then alongside Thor lying on the ground, probably overwhelmed in a clash.”
Source: Comic Book Movie