A thrill-packed melodrama of flying aces, foreign spies and modern romance opens at a christening of a giant airplane designed to pioneer trans-Atlantic travel service. Present are John R. Fleming (Ralph Morgan), builder of the plane; Ace Martin (Brian Donlevy), famous ace pilot who is to fly it; Joe Randall (Thomas Beck), the co-pilot; and Colonel Gimpy (Peter Lorre), half-mad cripple, "mascot" of the airport. Randall idolizes Martin, who is really the tool of a foreign spy ring. Martin tells Randall that Sidney Grant (Lester Matthews), the manufacturer for whom Randall's sweetheart Ruth Franklin (Helen Wood) works for, has stolen the plans for a propeller which he invented. That night, Randall steals the plans from her office, without her knowledge, and gives them to Martin. The same evening, Fleming discovers his wife is having an affair with Grant. Later, Fleming, Martin and Randall hop off on a secret flight across the Atlantic.