One of the world's finest musicians, according to the likes of Kurt Cobain and Beck, the late Daniel Johnston was a man whose life had been defined not only by his musical talent but by his struggle with mental illness. This is a riveting portrait sketched by those who know him best, from his first acid trip at a Butthole Surfers concert to his foray into the art world, with appearances by cult bands such as Sonic Youth, Jad Fair and Half Japanese.