Gustav and Alma Mahler arrived in New York City in 1907. He had been invited to lead the Metropolitan Opera; his glamorous wife accompanied him to the New World. His embattled American career places their legendary marriage in sharp relief. Nineteen years Gustav's junior, Alma was his constant companion and occasional soul-mate, sometimes his muse, always his caretaker, a woman otherwise restless and unfulfilled. Her husband's life was intensely interior,...