Here is what the storyline is about, as released by GW. Trailers and pics can be seen here http://www.ultramarinesthemovie.com/. This is also were you can order the movie which is already available for pre-order. Launch date is November 29th.
Captain Severus, a revered veteran warrior with a considerable reputation, has received an urgent request for assistance from the remote backwater planet Mithron. Mithron has only one site of strategic importance, a shrine defended for countless generations by a full company of Space Marines from the Imperial Fists Chapter. What dreadful fate could have overcome them that they ask for help?
Leaving the bulk of his company on Algol to prosecute the war against the nightmarish Tyranids, Severus sets off for Mithron with only a ten-man squad for support. Ultima Squad is a raw, untrained band of Battle-Brothers, all recently promoted from the ranks of Space Marine Scouts and thirsting for glory. Mithron will be their first taste of action as fully fledged Ultramarines. Severus, with his Sergeant Crastor and his apothecary Pythol, knows they'll need to keep a careful watch on the recruits.
For ambitious new recruits Proteus and Verenor, competitors for their captain's approval, the reality of the task ahead becomes clear. They want a glorious first taste of combat as fully fledged Space Marines to prove they are worthy of selection. But this mission is a savage fight for survival and, if the Ultramarines fail, events on Mithron will threaten the fate of millions of densely populated Imperial worlds starting with their fortress home of Macragge...
