Every time the terms "Dungeons & Dragons" and "story" appear together and I don't find myself in a 10x10 room with four other people, checking for traps, I'm just the tiniest bit disappointed.
This is Neverwinter, the action-MMO take on the classic franchise, as previewed by our own Kate Cox earlier this year. Specifically this is the Gamescom trailer for Neverwinter, now confirmed for an early 2013.
Perfect World Entertainment has the game playable at Gamescom. It's also playable at GenCon this weekend, and PAX Prime two weekends later. If you're at the first, give it a spin. If you're at the other two, maybe try to get into a game of D&D proper instead? I hear they have 10x10 rooms.