Zhang Yue (left), chairman of the Broad Sustainable Building Group, works in his office. Photo rovided to China Daily

Leading lady a true legend

It's all about making a spectacle

Wright, who has interviewed Zhang in the past, adds: "The West is full of big, planned, high-density estates, many of which became sink housing. But when you go to Chinese cities, people live in even higher towers, at higher densities - and everything is fine. So there is definitely a mentality difference."

Such dichotomous perspectives and questioning is where the film succeeds. Gronroos also says that she "wanted to make a film where the audience can smile a bit, because the subject is so heavy". She achieves this gracefully, with wit and charm, but the film is by no means perfect. By the close, Zhang and Paloheimo's narratives have diverged so much that the only solution, it seems, is to make a follow-on documentary, which the director is committed to doing - and indeed Zhang has invited her to do so. For now, though, Ecopolis leaves the audience with a large unknown as to the individual fates of Eco Valley and Sky City - but perhaps it is fitting, serving as a foreboding echo of the great uncertainty that is China's environmental future.

Ming Liu is a journalist for the Financial Times.