Hello. Sorry if I have posted in the wrong place, I am new to this forum.
I'm having some trouble with the summerset shadows quest. I have successfully started the quest, but after arriving at the Uttering Hills cave, there is no sign of the rival guild, the Shadows, Just bandits. Also, The locket I am supposed to find there is missing, so I can't complete the quest.
After killing the bandit chief there, I get a miscellaneous quest update, which may have something to do with it. Completing the miscellaneous quest after starting Summerset shadows seems to have no effect. Can anyone help me?

There are some bugs involved with this quest, it's best to check the bug list at the bottom of http://www.uesp.net/wiki/Skyrim:Summerset_Shadows article.

The best advice I can think of would be to reload from before you got the Summerset Shadows quest and clear the cave of the bandits for the misc. quest before you take the Summerset one.

It may be neccessary to stay away from the cell the cave is in for 31 days to allow it to reset, but I don't know that for certain.