Brian MacLean (James Cagney), Johnny Dutton (Dennis Morgan), "Tiny" Murphy (Alan Hale, Sr.), "Blimp" Lebec (George Tobias), and British expatriate "Scrounger" Harris (Reginald Gardiner) are bush pilots competing for business in rugged Northern Ontario, Canada in 1939, as the Second World War is beginning.
When two transport aircraft crash, killing all 44 ferry pilots aboard, there is a desperate call for pilots to ferry a group of unarmed Lockheed Hudson bombers from Gander, Newfoundland to Britain.