When tragedy strikes at the end of 1967, the Beatles are faced with an uncertain future. In the months and years to come, cracks begin to show in the foundations of the world’s most powerful musical unit. As each member matured and developed as artists, the end became inevitable.In Part 4 of Eras: The Beatles, Martin Freeman explores the pressures that broke the biggest band on the planet, and the incredible music that this turbulent era produced.From the high-minded psychedelia of Magical Mystery Tour to the drama of Let It Be, to the masterpiece that was Abbey Road, the BBC Archive team have scoured their collections to bring you the interviews that shine a light on a dark period for the Beatles.