Kazan, level 25 master of the thieve's guild, is east of Markarth on his way to meet Eola and clear the Namira shrine of Draugr. Stumbles across a cave and investigates. Finds a dead adventurer next to a pedestal with a note and a dragon claw. The note starts a quest with a name like "Forgotten Legend". Text of the note warns of the great price at which the nearby door was sealed. Using the claw to open the door leads only to a corridor closed by another dragon claw door. Hmm. Interesting quest to come back to later, I think. Then I check my quest log and it says that I've successfully recovered the fragments of the Amulet of Gauldr, or somesuch, and gone to his final resting place. Huh?

I know from my mage character that you find a Gauldr Amulet fragment somewhere early in the mage quest line. Saarthal maybe? Anyway, figure this must be a glitch. I think it's the second time I've had the quest journal reveal future developments in a quest line before I've actually accomplished them.

IIRC, the cave was hidden behind a waterfall.