The film is divided into three parts. The first part is set in the medium-sized town of Fenyangin 1999. 25-year-old shopkeeper Tao is torn between two suitors. Jingsheng is a well-off gas station owner whom she has little connection with but could drastically improve her material living conditions. She feels closer to Liangzi, a poor laborer in a local coal mine. When confronted by both men, Tao decides to marry Jingsheng in the hope of leaving Fenyang. In 2014, Tao is now divorced from Jingsheng and still living in Fenyang, running the prosperous gas station and being a prominent and generous woman in the city. Jingsheng has since remarried and lives in Shanghai, and has become wealthy from investments. Liangzi works as a miner near Handan, in the neighboring province of Hebei, and has gotten ill. Most of the second act focuses on Tao and Jingsheng's son, Daole aged 7, who comes to visit her for the funeral of her father. Tao is upset by Daole's distance, which she acknowledges is due to their cultural differences - a product of Jingsheng's fascination with globalization. Tao, knowing they are fated to be apart, decides to ride the slow train with Daole, instead of sending him on a plane back to Shanghai. As a parting gift, Tao makes Daole a set of keys for her house so that he can return to his mother's home whenever he wants. In 2025, Daole is attending college in Australia. He is constantly fighting with his father over his desire to drop out of college and have the freedom he was never granted in his childhood. He meets Mia, his Chinese language teacher, an older woman for whom he develops feelings and eventually begins a relationship with. Dollar shares with Mia how he still carries the keys his mother gave him when he was a young boy, and that he fears she may die, even though they have not talked for years. Mia convinces him to fly back to China with her so that he can see Tao. The film ends with Tao dancing to "Go West", recalling the beginning of the film when, as a young woman, she was dancing merrily with all of her then fellows, full of hope for a better life. Any reunion with Daole is not seen.
Mountains May Depart holds a 79/100 average on review aggregation site Metacritic. Peter Bradshaw of The Guardian wrote, "Jia Zhang-ke’s Mountains May Depart is a mysterious and in its way staggeringly ambitious piece of work from a film-maker whose creativity is evolving before our eyes." Scott Foundas of Variety states "Mountains May Depart is never less than a work of soaring ambition and deeply felt humanism, as Jia longs not so much to turn back the hands of time, but to ever so slightly slow them down." Derek Elley of Film Business Asia gave it a 5 out of 10, calling the film a "weakly written saga of friendship goes way off the rails in the final part."
Go West plays a prominent role in the film, as the film opens to a scene on New Year's Eve 1999 with Tao dancing to the song and closes in 2025 with a scene of Tao crying and dancing to the song near the old pagoda. In an interview with AV Club Zhangke states that he was attempting to evoke a "collective history for that generation."
