An Air Raid On Cologne
Adventure #4 in the collection . First published in Thomson's Weekly News 09/24/1918 and syndicated to the Glasgow Sunday Post, 09/29/1918.
A post card from a British POW in Germany, allowed in their normal mail, contained a message in invisible ink talking about another agent being captured and leaving a secret list on German losses in a hidey-hole. To learn more, John Frazer plans a trip to Cologne.