Fallout 4's Vault-Tec Workshop DLC, out on 26th July, is the first Workshop add-on with quests.
Here's how it all works. If you're above level 20, you'll hear a distress beacon no matter where you are in Bethesda's post-apocalyptic open world.
This alerts you to an emergency at Vault 88. There, you need to kill some Raiders who are trying to get in before meeting the Vault's estranged Overseer.
The Overseer is the only surviving resident of Vault 88. She turned into a ghoul because the bombs went off before her vault was finished, and has spent the last 200 years waiting to build it.
Here's where the quest begins. You have to interview potential new settlers as you hunt for subjects for your experiments. These experiments have different outcomes depending on the choices you make.
You don't have to complete the quests at all if you don't want to, Bethesda said. You can just kill the Overseer or tell her to leave when you arrive. If you do, you can still build a basic version of each experiment item.
The reason why you only hear the beacon if you're level 20 or above is because the space in which it takes place is minimum level 35. So, you can stumble into it below level 20, but it'll be rock hard. You'll probably die, Bethesda warned.
There are some useful things you can make in your Vault, such as the new Barber and Surgeon chairs. So you no longer need to go to Diamond City to change your look. Now, you can assign a settler to one of the chairs and get free haircuts and facial reconstruction surgery whenever you want.
It's worth noting that once you've finished up the questline, all the items you've unlocked for use in Vault 88 can be used above ground in other settlements, so you can create Vaults all over the world if you fancy it.