The cliche of classic rock guitar is one of riffs, solos and noise. But write a list of great guitarists and their finest moments and a quieter, more intense playing comes to the fore. The acoustic guitar is the secret weapon in the armoury of the guitar hero, when paradoxically they get more attention by playing quietly than being loud. This documentary takes an insightful and occasionally irreverent look at the love affair between rock and the humble acoustic guitar. Exploring a much less celebrated, yet crucial part of the rock musician's arsenal, contributors including Johnny Marr, Keith Richards, Ray Davies, James Dean Bradfield, Biffy Clyro, Joan Armatrading, Donovan and Roger McGuinn discuss why an instrument favoured by medieval minstrels and singing nuns is as important to rock 'n' roll as the drums, bass and its noisy sister, the electric guitar.