Cliff Walkers follows 4 Chinese spies trying to reach the Japanese-dominated city of Harbin, where they should await for further instructions. However, the Japanese are aware of their plans, and send their agents to infiltrate and sabotage the mission. This film has spies doing what they do best: handling information. The first scene has the protagonists split into 2 groups, with no radios or other ways to contact each other. In a following scene, when one of the groups learns that they're being watched, they must pass this information to their teammates without busting their identity. In another, they must schedule a meeting without seeing each other. The challenge of transmitting/receiving information is the base for the whole movie. The Japanese suspects they have a mole, so they're also careful when sharing information among them. The film goes back and forth like this, alternating between scenes following the Japanese or Chinese teams. All the characters are smart, and will play tricks to withhold or extract information from others. The tension starts at the 10-minute mark and lasts throughout the session. It feels exactly how a spy movie should. While the writer has said this is a movie where spies are "portrayed as people with emotions", I couldn't connect with any of the characters. But I wouldn't say this is a bad thing, I actually think it's good. There are moments where the tension will ease and the characters will shed tears or talk about their past, but they represent a minor slice of the movie's length (it lasts 2 hours). They use just enough time so that you don't feel like you're watching emotionless robots. But this means that the time not being used to make the spies more human is being used to build up the tension, which represents the absolute best aspect of this film. Unfortunately, I can't say I enjoyed the movie to it's fullest. There were moments where I couldn't absorb new information fast enough. All the characters wear the same clothes, which makes it kinda hard to know who is who. This leads to scenes where you don't understand what just happened. A character/event flowchart would be a welcome companion while watching it. From what I've been able to research, this is actually a prequel to the 2012 TV show "悬崖" (Cliff) by the same writer, Quan Yongxian. In an interview, he said that in 2015 he had written the script for this prequel as a 60-episode show. If this had been a TV show – or even a book –, where things could flow in a more friendly pace, this would've been an absolute must-watch. Overall, it's a very good movie, and I recommend anyone interested to watch it. Even though you'll scratch your head sometimes and may wish to rewind a bit to understand what is happening, the movie is perfectly enjoyable without an aforementioned flowchart.