The brooding, raw and groundbreaking performances Marlon Brando gave in such films as A Streetcar Named Desire, On the Waterfront and The Godfather gave the actor an iconic status, despite his lifelong disdain for acting. Alan Yentob talks to Martin Scorsese , Francis Ford Coppola and Bernardo Bertolucci - as well as the Adler family of New York, with whom he was long associated - to piece together a portrait of a highly complex man.