The short life of Robert Louis Stevenson (1850-94) was as adventurous as almost anything in his fiction: his travels, illness, struggles to become a writer, relationships with his volatile wife and step-family, friendships, and quarrels have fascinated readers for more than a century. He was both engineer and aesthete, dutiful son and reckless lover, Scotsman and South Sea Islander, Covenanter and atheist. Stevenson's books, including Treasure...