This movie is with the Chosun Dynasty in the years 1800's for setting. 
At that time,  there were two main political parties.  They have been thought to be pitted against each other for their own interests for power and wealth.  However, in this movie the point of view is adjusted to the conflict between them on the basis of the philosophical views of the world.   Both parties works and advocates their views for the wealthy country and peaceful life of people.  The different views, though. 
An official who is in charge of inspection and care for all the records by and about previous kings is found dead at the library of a government department.  And....the audience will enjoy this suspense thriller.