Parker Pyne is on a vacation in the Middle East and is soon to set off on the four-hundred mile journey across the Syrian Desert from Damascus to Baghdad by a Pullman motor coach that will traverse the wastes in some thirty-six hours instead of the months that the trip used to take. There are various other people sharing the journey including the young attractive Netta Pryce and her austere aunt; three Royal Air Force officers called O'Rourke, Loftus and Williamson; a Mr Hensley of the Baghdad public works department; an old Etonian called Captain Smethurst; General Poli, an Italian; and an Armenian mother and her son.