Spy Smasher and Captain Midnight were remarkably similar crimefighters who operated during the same period of World War II. Each were skilled aviators, masterful inventors, daring dogooders.
In 1943, while testing out his new aircraft, Midnight was involved with clashes versus Imperial Japanese forces in the skies. Calling out to his Secret Squadron code named "SS" on the airwaves, his transmission is received by Spy Smasher's equipment in his amazing Gyrosub vessel. Thinking the message was for him, he tracks the source and meet the Captsin.
What follows is a race around the globe to see which aircraft is the fastest on Earth-S, and have further encounters with their Japanese foes. The goggled good guys ultimately prove victorious versus their foes, parting as friends and allies.
Spy Smasher's counterpart Mister Terrific and Captain Midnight's doppleganger Doctor Mid-Nite teamed up in a case of the Justice Society of America in 1945. The Doctor was a regular meeting of the Society while Terrific was first an honorary member then later a full-fledged one.
While these Society teammates on Earth-Two didn't have fancy aircraft.. that would be owned by the Batman and Green Arrow of their world... they were just as courageous and tenacious.