when this combined with the beren legend it introduced felagund as beren 's companion , luthien 's imprisonment in nargothrond by celegorm and curufin , her escape with huan the hound of celegorm , and the attack on beren and luthien as they returned from tol-in- gaurhoth by celegorm and curufin , now fleeing from nargothrond ( the silmarillion pp .