Mason returned to India after the First World War and began preparing for his most important scientific project, the exploration of the Shaksgam Valley, in 1926. At that time the only westerner to see the valley had been Francis Younghusband, whose book "The heart of a continent : a narrative of travels in Manchuria, across the Gobi Desert, through the Himalayas, the Pamirs, and Chitral, 1884-1894" had first inspired Mason as a schoolboy to pursue a career in geography. Now, Younghusband encouraged Mason to follow in his footsteps.