'Look, I'm hardly pretty, he seems to say. I sound like gravel; I look rough and tough; and, honest, I don't give you the soft, foolish answers the pretty boys will give you. You may not like what I say, but you better believe it.' He became a legend as 'Bogie', the world-weary, wise-cracking outsider, but in reality Humphrey Bogart was plagued by doubts and demons. He was born upper-class yet made his name playing mavericks, drank with the rat pack and met four wives on set - including his great love, Lauren Bacall - yet always mistrusted stardom. Here David Thomson, one of film's most provocative writers, reveals the man behind cinema's greatest icon.