Peter Trafford is cataloguing manuscripts at a monastery in Tunisia, and is in love with Marcelle, the younger sister of two sisters of Artois, the proprietor of the hotel where he is staying. He finds an envelope containing an unfinished letter from one Hans Sleigman. This turns out to have been a German agent sent to subvert local Arabs against the British, and the letter gives instructions for finding the hoard of sovereigns he brought to bribe them, now hidden in some relation to a local landmark called "three oaks". He sets out to hunt for the treasure, but he is not the only one.
John Bull, 24 May 1958.
It also appeared with the title "Three Oaks" in the Toronto Star Weekly on 23 and 30 May, 1959.