Quest Help: Missing Dialouge/Item?

[ShajinE]

First I hope this is in the right forum now.  I must have clicked the wrong link or something before.  I am looking for the SD+ support forum.  And I apologize if it is in the wrong place.  Maybe it is a wrong link or redirect.  So if this is again in the wrong place please post the right link.  Thank You.

 

Ok I don't know if I am missing something or not with the "The Truth" quest.  My current stage in the quest is having to find the shrine to Sanguine under Honningbrew Meadery.  I read the Mead Stained Letter and found the trapdoor under the bridge.  The letter references a "disgruntal customer" in the sky district and a box in the mud somewhere.  I have talked to all the people up in dragonsreach and no one has any dialouge for this quest.  I scoured dragonsreach for a box that may have the key for the trapdoor in it but could not find that.  I looked around the meadery, the bridge, and inside the meadery as well.  The only way to get a key to the underground area is to start the thieves guild quest line for the meadery.  I really did not plan on doing anything with the thieves guild.  But I will if I have to.  So am I missing dialouge, the box, or am I supposed to wait around at the trapdoor at night and follow someone in.  Please point me in the right direction.  Thanks.