By making it clear that those who find themselves in these situations are all ordinary people just like us, Ai Weiwei brings home the sheer, unthinkable monstrousness of their predicament.

Its dazzling drone photography sends you gliding over vast expanses of ocean and desert yet the film itself leads to the inescapable conclusion that the world is shrinking.

What he shows us is tragic and horrifying, but he offers no possible solutions and nothing much in the way of analysis.

[The refugees'] situation is extreme, the risks dire, and they're real people. Was it obscene to parade them for my consumption, or was my irritation at his constantly inserting himself into the frame like Hitchcock beside the point?