This is the Brotherhood Lvl 4 section of the map of the wasteland presented by:
This is the elders level. Maxson is in the building nearest to the elevator. He will ask you to scout the north (the military base), when you take this mission you get a choice of some neat stuff from his assistant. Go to the military base and come back and he will ask you to join him in a councle with the elders. If you do so they will send a task squad with you to take out the guards. Be careful with what you say to Maxson, he has a temper too.