Dietrich Bonhoeffer was not even told why he was arrested!  The jailer said to him, “You will find out soon enough!”

I was taken to the most isolated cell on the top of the floor; a notice, prohibiting all access without special permission, was put outside of it.  I was told that all correspondence would be stopped until further notice, and that, unlike all the other prisoners, I should not be allowed half an hour a day in the open air, although, according to the prison rules, I was entitled to it.  I received neither news papers not anything to smoke.

(Mary Bosanquet, The Life and Death of Dietrich Bonhoeffer, 247)