Got ONE shot at doing something truly righteous?

There are variables that I cannot account for but I have a chance to do something very courageous and righteous. I may fail...I may die or worse and if i live I will have made many powerful enemies. I have no allies that I know of. But I cannot live my life afraid to do the right thing because those in power oppose justice. For thee record everything I intent to do is perfectly legal and moral. What would you do in a similar situation?