Board Thread:Skyrim/@comment-108.66.204.27-20130316232306/@comment-6528030-20130317145144

You may also travel to Windhelm and over hear a conversation between a woman and a boy about Aventus, they will be standing right near his home, here... http://elderscrolls.wikia.com/wiki/Aretino_Residence?file=AretinoResidenceMapMarker.png

Then just pick the lock to Aventuses home and proceed to talk to him.