Dispose of Jain

 is a side quest in the original Fallout.

Walkthrough
Decker gives this quest after you have succesfully Disposed of Daren Hightower. His next assignment is for you to kill the high priestess Jain of the Children of the Cathedral.

Go to the southeast exit grid in Downtown of the Hub. Enter the building toward the west in the next area, go into the back office, and kill the person in the purple robe. Be warned that this will cause everyone else in the building to become hostile.

Reward

 * 1000 Bottle caps upon agreeing to the task.
 * 4000 caps upon completion of the quest.