A kind of popular novel in which a protagonist endangered by a criminal or otherwise sinister conspiracy is followed through heroic adventures made up of flight, pursuit, capture, and escape. Although the genre has always been relatively loosely defined, it may still be distinguished from the detective story in that its interest in criminal activity concentrates on imminent dangers and evasive actions rather than on retrospective analysis or investigation, its atmosphere being more anxious and frenetic than that of detective fiction. The first significant novel of this kind was William Godwin's Things as They Are, or the Adventures of Caleb Williams (1794, better known simply as Caleb Williams), in which the hero is pursued by his former employer's agents after discovering an unnamed secret. Similar emphases on dark secrets and menacing intrigues are found in the sensation novels of the 1860s, but the modern thriller as an identifiable popular genre emerged from the early years of the 20th century, at which time John Buchan's books, notably The Thirty-Nine Steps (1915), set the standard to be followed, while Sax Rohmer in The Mystery of Dr Fu Manchu (1913) and its sequels showed the depths of inane xenophobia to which the genre could sink. A major subgenre is the spy thriller, practised by Buchan and others, further popularized by Ian Fleming in his James Bond novels (1953–63), and later raised to significant literary distinction by John Le Carré in The Spy Who Came in From the Cold (1963) and other works. The noir thriller is less clearly differentiated, but commonly leads the reader into identification with a criminal, as in several novels by Patricia Highsmith. For a fuller account, consult Jerry Palmer, Thrillers (1978).