Near the end of this engrossing documentary, when dissident Chinese artist Ai Weiwei is asked what makes him so fearless in challenging the state, he turns the question on its head, insisting that he acts only because he’s unusually fearful. The remark smacks of smug self-deprecation, but it may also come closer than anything else to explaining the ferocity of his PR assault on the government. Documentary maker Alison Klayman trails Ai from December 2008 to spring 2011 as he mounts shows in London and Berlin; amid all this professional activity he’s also beaten by police, forced to tear down his studio in Shanghai, and detained for almost three months as human rights proponents demand his release. As handy with Twitter as he is with sculpting tools, Ai admits that he’s become “a brand for liberal thinking and individualism,” though that’s nothing to be ashamed of—at this point his Warholian talent for self-promotion may be the only thing keeping him alive.