I've played through the first two campaigns ages ago, but unfortunately, I don't really remember the plot. All that I do recall is that this compilation starts as average, classic D&D campaign and then becomes gradually more original and interesting, especially in the Dreamcatcher series.

The author's website has some story blurbs if you click on the individual modules:

http://www.adamandjamie.com/nwn/ShadowlordsCampaign.asp

Thanks!