The luminous star of Mr. Smith Goes to Washington, Shane, and other classic films was, as the subtitle aptly puts it, ''the actress nobody knew.'' Jean Arthur (1900-91) kept her personal life private, disdained the Hollywood publicity machine, and was called ''difficult'' because of her perfectionism and remoteness from costars on the movie set. John Oller, a lawyer, tracked down kinsfolk and friends never before interviewed to capture the elusive personality of a free spirit best embodied in her favorite role, Peter Pan. Arthur herself might have appreciated his warm, respectful portrait. .,.''[An] insightful, painstakingly researched analysis of Arthur's life and career raises the curtain on the complex, conflicted person behind the screen persona...Captures the special shine of a unique star who turned out to be a genuine eccentric.'' -Chicago Tribune