Thirteenth Impression" with preface dated 1931 despite 1929 date at title page. Classic early espionage novel, considered to be the first modern thriller. With two maps and two charts. Despite being a rather late printing, this is a very difficult novel to find in vintage dustjacket. This copy with printed publisher's jacket with blurb by John Buchan at front panel. Near Fine in Good fragile dustjacket, chipped at top spine end and flap corners, lower spine end chipped half inch deep, lower fore-edge corner of front panel with inch sized chip.