Dancer Sergei Polunin gets a respectful and useful documentary, but we need a deeper investigation into this amazing dancer, hamstrung by his own demonsThis is a sympathetic, serviceable but respectfully unintrusive documentary about the Ukrainian dancer Sergei Polunin, who in 2010, at the staggeringly early age of 20, became the Royal Ballet's youngest ever principal. Two years later, he walked out, owing to a crisi…
