This morning, for no good reason, I have been thinking of an idea for a story which I am very unlikely to ever write, and it occurred to me that someone else might.
The setting is the trial of Joan of Arc. The protagonist is one of the English prosecutors, an intelligent, deeply believing catholic clergyman who has the job of proving that Joan is a witch in order that she can be burned at the stake. The problem is that he has concluded that not only is she not a witch, she is a saint, whom God, for his own mysterious reasons, has provided to the wrong side. It follows that if he goes on to carry out his assignment he will be committing a sin for which he will deserve, and get, an eternity in hell. He is a loyal Englishman but the price of loyalty is in this case rather high.
I do not know where the story goes from there. Suicide is a mortal sin, so not a very attractive solution to his problem. The best solution I have thought of so far is for him to report the problem to a superior who takes his secular obligations more seriously and his religious obligations less, make it plain that he intends to go public with his conclusions, go from there to a priest to whom he can make confession, then go home and wait for the assassin to show up.
But there are surely other, and possibly better, ways the plot could go.