It’s 1970 and the Beatles have broken up for good. But the battle over their legacy is just beginning, especially between longtime songwriting partners John Lennon and Paul McCartney. They argue, sometimes bitterly, over who really wrote their chart-topping songs. It’s a debate that becomes even more complicated when John is gunned down outside his home in 1980 — making him a rock ’n’ roll martyr, and leaving behind a void Paul will struggle for decades to fill.