Major Thorpe (writer and artist), Mort Leav (pencils), Al Bryant (inks)
Published in Jumbo Comics #30, Aug 1941 - 7 pagesZX-5 is trying to sneak into Austria via Switzerland and having trouble along the way. The guide helping him is killed by a sniper unhappy with 'snoopers'. A Nazi ski patrol blocks one way. The sister of the dead guide comes along to assist, They avoid an avalanche. All this to find and infiltrate a school for spies where the guards recognize him as ZX-5 but not the people running it.
Here are the pages I have of it.