From a Q & A at the publisher's website:
Q: You spent a decade piecing together the events in The Airmen and the Headhunters: A True Story of Lost Soldiers, Heroic Tribesmen and the Unlikeliest Rescue of World War II from hundreds of different sources. How did you first learn of this little-known but harrowing episode of World War II?Read the full Q & A.
JH: In 1992 I was sitting in the War Memorial Library in Canberra, Australia, going through the papers of Tom Harrisson. I was writing a book about him because he had led a little-known special operations unit behind enemy lines in Borneo in the middle of WWII. One of the documents I came across was a letter addressed to Major Harrisson that was written in the rounded Palmer Method handwriting taught in American schools in the 1940s. The letter was signed by nine U.S. airmen—some army, some navy, with their ranks and serial numbers—who were being hidden in the jungles of Borneo by natives. I knew then that there was a story here that had to be uncovered and told.
--Marshal Zeringue