Farkas (or Vilkas - I get them mixed up) sent me on a quest to a cave (I forget the name of it right now). I found the 'out' - a locked gate with the chain on the other side. But I can't get in to the 'in'. My husband is playing Skyrim too and on his quest there was a chain that opened a rock wall, but the chain isn't there for me. He says it's the start of rescuing Serana and the whole Dawnguard storyline. Any suggestions on how to make the chain appear? I only have one save game before my current one and I really don't want to start the game over again. It would be my fourth time.

Talk to Isran first. He will send you to the start of the cave. If you don't want to start Dawnguard, the entrance is inbetween the Hall of the Vigilantes, and the Shrine to Molag Bal, on a mountainside. The entrance is on a stairway, with a dropped torch on it.