In 1917, lifeguards Wilkie (Spencer Tracy) and Mitchell (George Cooper) who can not even swim, are trying to keep out of the war. When a man is drowning, U.S. Army Air Corps Sergeant Hogan (William Boyd) rescues the drowning man but they are quick to claim credit.
When the pair go to a Red Cross benefit boxing match, they again encounter the sergeant, billed as “One Punch” Hogan but Wilkie surprisingly knocks him out, before sneaking out with Mitchell, as a crowd gathers. The two friends swear they will never join the Army but relent and later, wind up in uniform, shovelling manure. Determined to find a way out, Wilkie and Mitchell desert and head off to South America, hopping in a manure truck leaving the base.
After stowing away on a ship, they find out they are on a troop ship with Army Air Corps pilots going to France. Wilkie and Mitchell pretend they want to fly and are sent to train at an American aviation field. Doing their best to not become pilots, while on guard duty, Wilkie competes with Sgt. Hogan for the attentions of Fifi (Yola d’Avril), a French performer. After a dustup at a nightclub, the two rivals make a quick exit, hiding in a car driven by Mary Way (Ann Dvorak). Startled by the men, she crashes, but all are unharmed. Wilkie and Hogan escort her to an inn for the evening. In the morning, Wilkie has breakfast with Mary and cons Hogan into fixing her car.
Military police looking for the two and come and arrest them, as well as Mary thought to be a spy. Wilkie, Hogan and Mary escape in an aircraft, but land in enemy territory and are captured. Accidentally releasing two bombs, they bomb a German munitions depot. The Air Corps colonel (Billy Bevan) sends a squadron to rescue the trio, with Mitchell scaring the Germans by his inept maneuvers.
After their rescue, the three heroes fly home but Wilkie again accidentally pulls the lever for the bomb release, this time bombing his own base.
Reviewer Mordaunt Hall at The New York Times, described the film as “… a boisterous affair, in which even the familiar mud-hole in the water is employed to arouse laughter. Yet, Mr. Boyd as Sergeant Hogan and Mr. Tracy as Private Wilkie attack their rôles with undeniable vigor. Many punches are exchanged and when that sort of thing gets tame a few bottles and glasses are broken, which is followed by automobile smash-ups and airplane crashes. Added to this there is the quasi-romantic side of the adventure, with Yola d’Avril and Ann Dvorak contributing their feminine wiles.
Aviation film historians Hardwick and Schnepf, however, noted that Sky Devils was an example where “Howard Hughes figured he had made such a score with ‘Hell’s Angels/, he’d try it again with much of the same aerial footage and new stars. It bombed.
This film is one of over 200 titles in the list of independent feature films made available for television presentation by Advance Television Pictures announced in Motion Picture Herald 4 April 1942. At this time, television broadcasting was in its infancy, almost totally curtailed by the advent of World War II, and would not continue to develop until 1945-1946.