With little to live on but her romantic daydreams - which frequently starred the dashing Marquess of Fleetwater - Jean Lindsay lived a rather dismal life with her nasty, drunken uncle. Jean was always the object of ridicule, that is, until news of her unexpected inheritance spread. Suddenly her worn dresses became ''quaint'' and her forthright manner turned magically to ''charming,'' but to Jean's horror, someone wanted her dead! With the marquess nearby to save her pretty neck, Jean felt quite safe . . . and quite smitten. As for her hero . . . how had an unsophisticated child from a Scottish manse turned his head and his heart askew?