When John Lennon telephoned his old Hamburg friend Klaus Voormann in the spring of 1966, the German artist very nearly turned him down. After hearing rough tracks at Abbey Road, Voormann understood that dressing this music would be, in his own words, "a tough job." It sounded decades ahead of anything a pop group had attempted.

Lennon had a precise wish: he wanted the band's famous hair to be the focus, and he insisted on stark black and white to cut against the color explosion of the moment. "Now people are going crazy with the psychedelic look, whatever you call it, 'flower power,' but let's do it different this time, we'll do it black and white," Voormann recalled.

What emerged were four line-drawn faces of The Beatles, their manes swelling into thickets of ink, and from that hair small photographic faces spill out like memories shaken loose. There is no band name at all, only the title, Revolver. Look closely and a fifth face hides in the tangle, watching. How that thicket was built, and what all those tumbling faces were meant to say, comes next.