Some questions:
What makes great Rock'n'Roll bands work?
Why and how do they do what they do?
Why are the best bands more than the sum of their parts?
Why do we love them so much? What is the DNA of a great rock 'n' roll band?
The series breaks this mythical beast down into its constituent parts: singer, guitarist, drummer as well as the shadowy 'other one', whose face we don't quite know but without whom the magic wouldn't happen. The evidence is examined closely in forensic studies of what makes these rock 'n' roll types tick.

Part 4: The Other One
Meet the band's secret weapon: 'the other one'. They might play bass; maybe keyboards; sometimes it's not clear what they do at all. Underestimate them with peril though, these guys are the glue holding the band together. Stepping out from the sidelines are bassists Peter Hook of New Order and Duff McKagan of Guns N' Roses, keyboard players Rick Wakeman and The Doors' Ray Manzarek, plus the Happy Mondays' lord of the dance, Bez.