From the campaign:
Return to the Haunted Highlands Kickstarter includes two books (and possibly more) and a Map.
The Castle Keeper's Guide to the Highlands, 200+ pages: Includes all relevant setting material, adventures (DB1-DB6 expanded and updated), new monsters and more.
A Players Guide to the Highlands, 76+: includes racial variants, class specializations, new spells, magic and more (also includes expanded and updated material from the Black Libram).
Maps: 12 x 18 full color Map of the Haunted Highlands.