German Alps is the Chapter 0 or Prologue of Wolfenstein: The Old Blood. The mainly part of this chapter is just a context about what will happen in the rest of the campaign, with only the last section part of the real gameplay.
As part of the Operation: Wolfstone, the OSA agents William Joseph Blazkowicz and Richard Wesley (known also as Agent One) have been disguised as nazi officers in 1946 to infiltrate in the Castle Wolfenstein, HQ from Helga Von Schabbs, leader of the SS Paranormal Division. While they were travelling on car across the alps in annexed Austria, Wesley explain to Blazko what's going on with the war and the main plan. Their objetive is find a folder that contains the classified ubication of Deathshead compound to prepare a massive assault that changes the war course.
When they park the car, Agent One warns to B.J. don't talk, because his german accent is lousy. Fortunately, both pass the control room to the cablecar without problems, even after Blazko met by chance with Helga's second-in-command, Rudi Jäger. Once inside the castle, Wesley left B.J. on a plaftorm to reach each on their own a way to the Research Centre. After finding the safe of Helga, Wesley takes in count that folder isn't in the castle. Then he asks to his partner to contact Ludwig Kessler, their spy on the nearly village of Paderborn. Blazko used the radio to talk with Kessler, but they were discovered when the transmition overs.
With the cover ruined, Blazkowicz is forced to fight againts nazi soldiers while Agent One searchs an exit. After defeat the squads, Wesley deploys a ladder to help Blazko to go up to the second floor. Trying to escape by a ventilation duct, both agents fell on a trap where they were captured by Rudi, his dog Greta and a Supersoldaten that knocks Blazko before taking them to the dungeon.