Session Aces. Keepers of Time. Vocalists. Composers. The sidemen and sidewomen who play the riffs and fills we imitate in the air. When we turn up the radio, chances are we are listening to one of these players. A-listers have them on speed dial. International tour or recording session, who're they gonna call? A "Hired Gun." This feature length one-off documentary introduces the prolific musicians who are virtually unknown to the public. Billy Joel, Whitesnake, P!NK and Metallica are synonymous...