The Scarlet Squadron

Originally released serially in two issues of Boys Own Paper, October and November, 1927. Released as The Squadron of Death in paperback format in Boys' Wonder Library #1, July 1932. Released in book format in 1938.
After word comes to British Secret Service that "a certain foreign power was casting envious eyes upon our possessions in the East", Harry Davies, aka The Flying Beetle, was sent to China to investigate and he reported "the rumors were well founded and that Britain and the security of the Empire were being seriously menaced". When "all communications with Davies ceased", Major Beverley is told to head there to learn what happened to the famous secret agent.