“Operation Tokyo” by Ted Middleton. Published in 1956, the story is set in Japan during the Korean War. Naval Lt/Commander Emerson Thackeray Higgins is a pilot billeted with two other officers. One dies in a plane crash, and the other one leaves a note indicating suicide, but he is missing. Navy Intelligence (ONI) is investigating, and brings in Higgins for questioning, though he isn’t a suspect in the odd things happening on the Naval base at Tanikawa. Still, there is something strange. Higgins is further drawn into the case when his girl, a secretary at the State Department in Tokyo, appears involved in the mystery in some way. It turns out that the office did not commit suicide, but had discovered a secret in tunnels running beneath the base, where a treasure was buried. His squadron was preparing to ship out to Korea, and he figured it was time to disappear – with the treasure, if he can find it. This novel came out about the same time as “Tokyo Intrigue” by William Bender, whose main character was an Air Force pilot, but wasn’t as good as “Tokyo Intrigue”, and didn’t have as many interesting characters. Other than the plots, however, the two stories are quite similar.