Now i'm not sure if this is legit or i'm just misinterpreting it, but i found a casting website for Warcraft that lists some of the story. This is not the same as what we heard at Blizzcon (Durotan/Lothar) so that is why i'm skeptical. Either way, either of these stories is good, here's the link: http://www.acting-auditions.org/2013...e-film_29.html (scroll to the bottom of the page where it reads "story:"
Basically it's suggesting a movie about the Lich King and Arthas's story