The book challenges both popular and scholarly portrayals of Malcolm X, the black nationalist leader, describing a man often subject to doubts about theology, politics and other matters, quite different from the figure of unswerving moral certitude that became an enduring symbol of African-American pride.
It is particularly critical of the celebrated “Autobiography of Malcolm X,” now a staple of college reading lists, which was written with Alex Haley and which Mr. Marable described as “fictive.” Drawing on diaries, private correspondence and surveillance records to a much greater extent than previous biographies, his book also suggests that the New York City Police Department and the F.B.I. had advance knowledge of Malcolm X’s assassination but allowed it to happen and then deliberately bungled the investigation.
The full article is available here. And for an unmediated experience of Marable's subject, see Malcolm X's famous commentary at the Oxford Union in 1964, here.