At the height of their popularity, the Beatles discover a new source of inspiration: LSD. As John Lennon becomes increasingly engrossed in his acid trips, Paul McCartney steps up and begins to take greater control of the band — which John, when he comes back down to earth, isn’t too happy about. But no matter where their heads are at, the two longtime partners come together to push their band’s sound in ever more experimental directions, leading to their twin masterpieces: Revolver and Sgt. Pepper’s Lonely Hearts Club Band.