Major Thorpe (writer and artist), Mort Leav (pencils and inks)
Published in Jumbo Comics #36, Feb 1942 - 8 pagesEvidence of sabotage at US air bases under construction in the "West Indian" gets ZX-5 sent there to investigate. He definitely finds trouble and death. A woman claiming to be Agatha Thistlewaite, daughter of the governor, proves to be a very dangerous adversary, as are fifth columnists seemingly everywhere.
Here are the pages I have of it.