Blackwood, as chapter, was released in 2021 and brings us back to Daedric realms after a long time. Also called the Gates of Oblivion storyline, Mehrunes Dagon is the central focus in this story arc. But first it will lead you to Leyawiin which is in Blackwood, the zone, which needs help in investigating a threat against former Imperial councilors and the activities of a Mehrunes Dagon cult.
You will have to seek the leader of the Ivory Brigade in Leyawiin, the capital of Blackwood.You can either teleport to Leyawiin, or pick up the quest from the Collections tab.