The Untamed spinoff: Fatal Journey is worth to watch for anyone who loves The Untamed and especially the Nie brothers.
When starting the movie, you got to give it some slack since the movie is only under 1h 30 mins long. The budget is on the low side, but if you really like the story of The Untamed, it helps you understand Nie Huaisang better. I suggest watching The Untamed fully to be able to understand anything in this movie.

STORY:
This movie tells about the relationship of the Nie brothers, Nie Mingjue and Nie Huaisang.
The story is about Nie Mingjue, Nie Huaisang and Nie clan's disciplines going to their Sword Sacrificial hall, the Nie clan's ancestral hall for their clan's sabers. The brothers need to seal their clan's sword spirit, as it is creating trouble.

MY OPINION:
The story itself is okay, I liked seeing Jin Guangyao, Nie Huaisang and Nie Mingjue again. We get some more background info on Nie Huaisang's and Nie Mingjue's relationship. We get to understand how important Nie Mingjue really is to Nie Huaisang and how intelligent he really is. I was a little disappointed on how Nie Huaisang found out about Jin Guangyao being the bad guy. The movie felt a little boring to me, as I felt like there was not much going on. Everything was dealt quickly except for the fight scenes. I wish there was more interaction between the brothers and Jin Guangyao instead of them running from danger in their sword sacrificial hall. The CGI was not great, and I wasn't a fan of the CGI on the instruments when they were playing.

I would give it a solid 7.