A pregnant American nurse living in London during WWI, believing her soldier-fiance has been killed in France, marries a wealthy aristocrat so her child will have a father.

The stooges are auto mechanics working for the R.A.F. in England. After wrecking an officers car they need a place to hide, but their choice, a sewer pipe, turns out to a bomb which is dropped on the enemy. Finding themselves behind enemy lines, Moe and Curly disguise as German officers and Larry dresses as a seductive fraulein. While general Bommel chases after Larry, Moe and Curly steal the secret plans from the high command.