Murkmire released in late October, 2018, and concerns a previously unexplored region of Black Marsh, the story is about an dead clan of argonians.
Source: Wikipedia, "[en.wikipedia.org/wiki/The_Elder_Scrolls_Online%23Downloadable_content The Elder Scrolls Online]", available under the CC-BY-SA License.
Investigate Murkmire's long-forgotten past and help an Imperial scholar recover a mysterious and powerful relic in a new main quest line that takes you deep into Black Marsh, its history, and its people.
Source: The Publisher Website.