Mark David Chapman was one of the most invisible.

By the end of 1980, the Beatles had been broken up for a decade -- a decade John Lennon had spent in search of his true identity: singer, songwriter, activist, burn out. But now, he declared, it's the perfect time to be coming back.

Except that Lennon was a marked man. As early as the Beatles' controversial 1966 American tour, during which the band had feared for their safety, Lennon had complained, You might as well put a target on me. The Nixon administration did just that, putting Lennon under FBI surveillance. If only the agents hadn't been so intently focused on the star himself, they might have detected Mark David Chapman's powerful, ever-growing obsession with the man he'd grown up idolizing.

Chapman, himself a tragic nowhere man, ultimately achieved the notoriety he craved by making the target on Lennon very real -- and single-handedly wounding the spirit of a generation.