Robert Louis Stevenson has proved to be as elusive as that childhood shadow and his works move in and out of our cultural consciousness without--as the late James Pope Hennessy contends here--""making an indelible impression on your mind. . . you seem each time to be reading him afresh."" But Hennessy also feels that at the time of his death at 44, Stevenson was just beginning to move to a new maturity in his fiction. This admirably discreet biography lacks all the certitude of say, Edward Rice's Journey to Upolu (1974) which made much of Stevenson's ""bohemian"" proclivities. Hennessy does record the writer's theological storms with his Calvinist father, his youthful hijinks in Edinburgh while studying law, his habitually slovenly dress, his restless wanderings in Europe and America, and the last controversial years in Samoa. But Stevenson's incessant journeying seems to have proceeded less from an assumed life style than from an edgy nomadic bent, and in later years, from a preoccupation with his health and a possible cure--for fourteen years he was a semi-invalid. Hennessy not only acts as a tourist guide to Stevenson's many habitats, but he suggests plausible specific influences on the fiction and essays: early impressions of Scottish seacoasts (Stevenson's father was a lighthouse engineer); childhood play with a puppet theatre; exotic landscapes and Stevenson's involvement with nightmares and ""story"" dreams-- particularly those of pursuit and escape. Hennessy has little use for the writer's American wife, Fanny. Her self-puffery re her role as Stevenson's literary critic (""pretentious and aglay"") and disruptive moodiness during Stevenson's last years were, the author feels, something of a burden. But Stevenson (""the great exhilarator"") was a man of immense charm, not unattractive vanity and feverish courage. Stevenson once wrote of his fiction "". . . it is a small age and I am of it. . . I cannot take myself seriously . . . ."" An exemplary touchstone for all master storytellers.