It is a sad fact of life that truth so often is not welcome and that many people pay a very heavy price for it. Does this mean we shouldn't portray this in fiction? I think not. Where it is appropriate to the story to do so, I think you should portray it. Indeed, it would be difficult not to given every hero has to have something to be a hero about and so often it usually is fighting for the truth about something to come out etc.
So the story here then is what is the truth as it relates to your characters and their world? Why is it being suppressed and by whom? How does your hero/heroine ensure the truth does come out? What price do they pay for doing this (and there is bound to be one, probably a very heavy one at that. I always liked the ending of The Lord of the Rings where it is made very clear Frodo has been changed so much by his adventures, that more change, another journey, is necessary for him. I don't really want to say more than that in case you haven't read it or seen the films).