"The Night Owl" is one of the best fact-ion (facts+fiction) sageuk I have seen so far. Using In Jo's infamous reign and Crown Prince So Hyeon's death as part of the plot, it develops an original story around an atypical character.
I like historical movies that stick to the facts as much as possible very much, but I also like a well made fiction based on historical events when it is cleverly made, just like this movie. I don't think it's a thriller though, only a good sageuk with some thrills. I'm not usually keen for humour in sageuk, but the few little scenes in this movie were actually good and well made.
The cast is very good and all the actors are really good in their respective roles. Actors like Yoo Hae Jin, Jo Sung Ha and Choi Moo Sung, as usual, never disappoint, and Ryu Joon Yeol is excellent as Kyung Soo, and special mention for Kim Sung Cheol too that is really good in this role too.
The music isn't very special or grandiose, but it's good, and the aesthetic of the movie quite beautiful with an overall production very well made so I give it a pretty high ratings.