In April 2011, China`s most famous artist was scooped up at Beijing airport by government officials, and held in secret detention for 81 days. The biggest surprise was that it had not happened sooner. As the absorbing Never Sorry shows, Ai Weiwei had for years been one of the ruling party`s most trenchant, irrepressible and charismatic critics. He disowned his part in the design of the Beijing Olympics` `Bird`s Nest` Stadium in protest at the treatment of the city's residents. He challenged the official response to the 2008 Sichuan earthquake by compiling a list of the names of the thousands of students whose deaths had gone unacknowledged. And he defiantly tweets and documents everything online.