In 1915, at the height of World War I, the Central Powers sent a secret mission, led by Oskar Ritter von Niedermayer and Werner Otto von Hentig, to the court of the emir of Afghanistan, Habibullah Khan. Jointly operated by the governments of Germany and Turkey, the aim of the mission was to persuade the emir to declare full independence from the British Empire, enter the war on the side of the Central Powers and attack British India. Britain saw this mission as a serious and credible threat - so much so that they tried to intercept the travellers in Persia en route to Kabul and subsequently implemented their own intelligence mission to ensure that Afghanistan would retain its neutral position. Jules Stewart provides a gripping account of the expedition, highlighting a previously little-known aspect of World War I.