A Yahoo! interviewer at SDCC asked Tom Hiddleston what Thor 2 was about and he got one heck of an answer. It involved Hasbro action figures of Thor, Loki and Malekith (the Big Bad played by Christopher Eccleston).
See those, along with the video after the break.
No need to worry about spoilers, unless you’re totally unclear on the enmity between the Asgardian brothers. If so, then “whoops”.