In addition to the announcement that Diablo III would be free for all World of Warcraft subscribers with an annual pass, Blizzard showed off a cinematic from the game, titled "The Black Soulstone".
In it, the character Leah (voiced by FemShep herself, Jennifer Hale), narrates, reading through her uncle's books, trying to figure out what it is that she's missing. Suddenly, she awakens in a hellish throneroom, where she faces off against a giant demon. "You thought you were so clever," said the demon. "One by one, our bretheren fell into our trap. But not me. I defy you! I know the Black Soulstone is the key, and it shall be mine!"
The demon then makes a bunch of apocalyptic promises, and things get very "Lord of the Rings march of the forces of Sauron"-y. Woah, man.