The Chinese spy thriller “Cliff Walkers” is and isn’t as chilly and straight-forward as it seems. Directed by Zhang Yimou (“Hero,” “Shadow”) and set in Northeastern China during 1931, “Cliff Walkers” follows four Chinese spies as they struggle to execute a covert op: identify and rescue a Chinese informer from the brutal occupying Japanese army. These four protagonists are cyphers who are defined by their elegant, spare wardrobe—black overcoats with matching hats—and their heroic resolve to evade capture before arriving at Harbin, their ultimate destination. Advertisement This sort of spartan chase narrative (co-adapted by Quan Yongxian and Zhang) is as relentless as it is grim: characters’ backstories are tucked into asides during otherwise negligible dialogue exchanges, and there are only a few moments of tension-relieving humor. I’m not entirely convinced that there’s more to “Cliff Walkers” beneath its captivating, glassy surfaces. But maybe there doesn’t need to be, not when Zhang and his collaborators seem to have accomplished everything that they set out to.