This is fantastic; I love the slow reveal of what's really going on, and Dean and Sam's subtle shifts in personality and action as time passes. And how Sam knew exactly how Dean would react if he had known and instead did his damndest to make sure things went the way Sam wanted them too. It's such a perfectly Sam thing to do. Also, I am a huge sucker for unreliable narrators (and had never really put that together until monkeycrackmary mentioned it) and this story totally rocked that; I loved Dean's perspective and how we learn what's going on at the same time he does. It's just such an effective narrative style for a story like this; wonderfully suspenseful.

The only things I don't get, and I think this speaks more to my lack of werewolf mythology than any obtuse writing on your part, but what was up with the buried silver?