Captain Gillis (Frank Faylen) puts Sergeant "Dodo" Doubleday (William Tracy), because of his photographic memory, on a candidates list for Officer's Training School ahead of Sergeant William Ames (Joe Sawyer), much to the dismay of the Ames. The latter, in an effort to make Doubleday look bad, puts him in charge of the training of the Hatfield clan, a raw-to-the-max group of recruits from Kentucky. That they are all sharp-shooters does Doubleday no harm. Meanwhile, across town, a highly-respected citizen named Arnold Benedict (Clyde Filmore) and his tall squeeze Lydia (Rebel Randall) open up an in-house canteen for the soldiers. That Arnold is a German Spy comes as no great surprise to students of American history or Hal Roach films. Joan (Jean Porter), Dodo's girl friend (and ample proof that Dodo is smarter than he looks and acts), discovers that all the house-plants in the house are armed with listening devices feeding directly to the basement where most of Hollywood's German-actor colony (most under WWII assumed non-de-plumes) are eavesdropping on the conversations of the soldiers. While Dodo and his MP band of Hatfields are cleaning out this nest of spys, Dodo hears a message on the short-wave announcing the locations and meeting places of all the 5th Column spy rings and, because of his photographic memory, there will be no problem passing this info onto Colonel Elliott (Robert Barrat.) And there wouldn't have been if Dodo hadn't got knocked out and lost his memory.