Not of This World Not of This World is a main quest and achievement / trophy in the " Fallout 3 " add - on " Mothership Zeta " . Detailed walkthrough . The abduction . The quest can be obtained at any point of the game from the time the player leaves Vault 101 , the same as all other " Fallout 3 " add - ons except for " Broken Steel " . You receive an unintelligible radio transmission which will lead you to the alien crash site , where you will be abducted by the alien s . The fastest way to get to the crash site is travel to Greener Pastures Disposal Site , and head northwest . If you haven ' t found Greener Pastures , travel to MDPL - 13 Power Station and head directly north . You should be exposed to significantly less radiation when traveling from MDPL - 13 . After being abducted , you will be probed by the aliens , who then direct a robotic arm equipped with a laser - like device to start moving down the table towards you . The screen flashes red , and you drift to unconsciousness . You will wake up in a cell , stripped of all your gear , with a woman from the Capital Wasteland named Somah . She will suggest staging a fist - fight as a ruse to attract the attention of the guards , so that you can overpower them and escape . Once you and Somah have exchanged a few punches , two aliens will enter the cell and she will help you beat them up . You may wish to pick up one of their shock baton s to arm yourself . After you and Somah have escaped , be sure to check out the contents of the other cells : a dead Enclave officer and a confused Rivet City security guard who is trying to convince herself she ' s just dreaming . The escape . Not long after you and Somah escape , you ' ll come across a caged cell holding a young girl named Sally . She requests that you free her by overloading and overheating the module near her cell . To do this , you need to activate the three cylinders surrounding the module down the hall . Once it explodes , Sally will open the previously sealed door by climbing through small ducts in the walls . She will then offer herself as a guide and help lead you throughout the ship . Somah says she will be staying behind to " watch your back " and that she ' ll catch up later . Your gear may be retrieved from a container located in a storage room to your left down the hall . You must now make your way through the fairly linear path with Sally helping you along the way . Not long afterwards you both alert some alien guards ( which appear as friendly dots on the compass , for now ) , who will spawn nearby and Sally tells you to wait . You have the option of asking Sally to assist you by giving her a grenade ( only frag or plasma can be given ) so that she may sneak up on them from behind the walls and hit them with the grenade after you distract them . Otherwise , you can deal with them on your own and she ' ll crawl anyway behind the walls . It may be a good idea to let her assist you , as the three aliens will all die immediately from her grenade as soon as you approach them , saving you the trouble . Sally will continue offering you assistance as you continue through the ship , such as unlocking doors or creating distractions to make your trip easier . You don ' t always have to accept her help , though . You may opt to just cut a bloody path during your escape , which will also provide a lot of alien loot and weaponry , such as alien epoxy , alien power module s , and interesting new weapons . During your escape you ' ll eventually encounter alien worker s . Sally informs you that it would be better to leave the harmless aliens alone . Killing them earns you negative Karma .