From Beatle mania to Beliebers, behind every success story there is an army of fans, most just want to show their appreciation, some take it further to prove their dedication but there is an elite group who go above and beyond the rest, they push the boundaries and walk the line between keen interest and life changing obsession, but why?

In this BBC film Tom Felton, who played the villainous Draco Malfoy in the massively successful movie franchise Harry Potter, meets up with some of these superfans, to have a go himself in order to get a better understanding of what drives people to become superfans.