What's the secret of Britney's intense emotional bond with her fans?  What do they get in return for their devotion and where does devotion cross over into obsession? And how does it all come together in Britain's biggest ever mass dance tribute to Britney?  The answers to these questions, and more, can be found in this endlessly surprising, original and wildly entertaining one-hour BBC Three documentary.  Directed by Oscar and RTS winning film-maker Vikram Jayanti ('When We Were Kings', 'Game Over: Kasparov & the Machine'; 'The Agony and the Ecstasy of Phil Spector').