Directed by Yung Chang. Distributed by Zeitgeist Films. 1 hour, 33 mins.

No MPAA rating

(adult themes). Playing at: Ritz Bourse.

Myth and reality, past and present, tradition and progress go head to head in Yung Chang's remarkable documentary about China's longest river, Up the Yangtze.

The Chinese Canadian director's lyrical, and at turns tragic, film explores the changes so-far wrought by the controversial Three Gorges Dam, a 600-foot-high monster that will eventually swallow up the river and its surrounding landscape. Started in 1994 and scheduled to be completed by 2011, the dam will be the largest hydroelectric project in the world.

As the river rises and expands to its full potential - imagine the Grand Canyon transformed into a lake, Chang says - it will require the relocation of two million people. Entire cities will be submerged, including Feng Du - or Ghost City as it is traditionally known - which according to legend, is a way station for the souls of the recently departed.

Chang moves back and forth between two stories. He follows a luxury boat filled with English-speaking tourists as it glides upriver on a "farewell tour." And he offers an intimate portrait of a family living on the riverbank. The coming flood threatens to destroy their home, a shabby hut made of discarded bits of tin and wood.

The twin narrative beautifully encapsulates the problems faced by China as it transforms itself into an economic powerhouse. It's an issue of vital importance not only for the Chinese, but for the international community.

- Tirdad Derakhshani