The campaign starts in the city of Hiltmarch, which since the end of the war has become a home to all races, even though the elves and dwarves currently have their own homes. The artificers have finished constructing devices that will distribute the “cure” to the rest of the realm in order to remove the corruption left from the demon invasion.

The process of this cure is that it needs to be carried through the lands, slowly radiating out from where it passes at about a rate of 1 mile a month. An expedition is then organized to reclaim the port city of Rotterdam, carrying the cure along with the caravan. With the construction of the shipyards at Portsmouth, the hope is to get Rotterdam ready for new citizens by the time the first boats can make it there. Rotterdam is also on the other side of the continent, total a 6 month journey, if all goes well.

Take a look at t wiki. There is some more helpful info there.

The Rebuilding of Hiltmarch