In the early 1930s, Spencer Tracy's truculent attitude and thunderingly aberrant behavior were his only defenses against studio power brokers who cast him as stereotypical con men, buddies and gangsters. But by the end of the decade the actor's on-screen style--seamless naturalism and subtle inflections--had proved the ticket to stardom. A Tracy performance was always more than just action; there was always an undercurrent of mental activity beneath the surface. Stanley Kramer, who directed him in several films, recalls: "I was afraid to say, 'Spencer, you're a great actor. He'd only say, 'Now
