This season 7 week 4 legendary quest requires you to collect a doomsday preppers guide.

Looks like Farmer Steel was right to worry about the alien invasion at the end of season 6. It seems he has gone missing and the week 4 legendary quests all revolve around investigating his disappearance.

There are 2 doomsday preppers guides located on the island.

The first is located in a building at Steamy Stacks. The building is a small building next to the reboot van.

The second is located in the Hydro 16 dam control building. There is an office on the ground floor that has the doomsday prepper inside.

See the maps and video below for the precise locations.

Steamy Stacks

Hydro 16

Map credit to fortnite.gg