Ok, will dance around dropping spoilers, but this is a question of honor vaguely inspired by A Song of Ice and Fire/Game of Thrones. For the sake of those intending to read/watch, I will not go into details, and keep it as vague as possible.
So, the situation is this:
Your liege lord, who you are sworn to obey and protect to the death, is under attack without hope of victory. In order to cause as much damage to those who have wronged him as possible, he orders that the city that is his capitol be set aflame, burning not only the attacking armies but the people who have made the city their home. However, there is only yourself, and the man who he has just given this order to present for this command.
Is it better to follow the directive of your liege, or to put a stop to it, forswearing your vow of obedience in the process?
(Sorry for the vagueness, but I truly don't wish to spoil plot information for anyone)