With the adventure coming out in just a few days (September 8th), WotC's Chris Perkins summarises the concept and drops a few hints.
[video=youtube;6cyANArcQYw]https://www.youtube.com/watch?v=6cyANArcQYw[/video]
[video=youtube;6cyANArcQYw]https://www.youtube.com/watch?v=6cyANArcQYw[/video]