“The world of the theatre is cruel,” the ballet master Boris Akimov says at one point, with a fatalistic shrug. Akimov has spent his entire career at the Bolshoi since joining the corps de ballet, in 1965; for a couple of years in the early two-thousands, he even directed the company. He has seen it all: the dashed ambitions and bitterness, as well as the fleeting triumphs.