Published in The Triumph #517-#525, 9 issues from September 15 to November 10 1934 with 3 pages believed in each issue.
Vital documents were stolen from the British Tank Corps Headquarters and transported behind enemy lines. It fell to Captain John Silence, the King of Spies, to head into danger there and get the documents back. Along the way he encounters a British pilot who had been shot down and needs help getting back
Note: I have found only one of the 9 issues so far. The three pages shown here are from the penultimate issue of the group, issue #524.