Your encounter with these cultists in one of the major towns, start the DLC Skyrim: Dragonborn
Background[edit]
Cultists of Miraak come searching for the "False Dragonborn" which they think is you, as opposed to the "True Dragonborn"
Actions[edit]
Talk to the cultists, then fight them
Cultist Orders[edit]
After you have beaten them. loot and read the Cultists' Orders they are carrying