Published in Jumbo Comics #22, Dec 1940 - 8 pages
A surprise air attack by a neighboring country destroys a small city in the country of Finia. It is suddenly in need of a "super-plane" to defend itself. The plans for that aircraft are help by ZX-5 who has them in his safe. Spymaster Baron Rathskull and his men are determined to get them from him.
Note: the style and feel of this comic, plus the use of the name of the original 'writer' makes me think this was a unused story from the early days.