The next Elder Scrolls Online update, the Dark Brotherhood, is going to come in two parts. As with Bethesda's previous updates, the new update will have a DLC game pack and the base game patch. As you can see in the official news, the update has a lot of changes for both parts. The most outstanding feature is, of course, the opportunity to become an assassin for hire in the Dark Brotherhood.
In celebration of the announcement, Bethesda has released a first look trailer about the Dark Brotherhood: