Basically, it's Fred Astaire joins the army. Co-starring Rita Hayworth.
The story in this type of film is never the most important thing, but here it's even flimsier than usual. Some silliness about Astaire's married boss having an eye on Hayworth, and to avoid suspicions from his wife he brings Astaire into the picture, who to get away from it all enlists in the army. Or something. Most of the humour in the film doesn't work. The film has two characters that are supposed to bring comic relief, but they don't. The flashlight scene is supposed to be funny, but it isn't. The musical numbers aren't too bad, though. Rita Hayworth is a good dancer, but she doesn't really achieve the sort of alchemy with Astaire that he and Rogers did. I'm not sure why. She might be too goodlooking and unreachable next to Fred. Ginger Rogers seemed more real, somehow.
Some of the magic of those films is that the goofylooking Astaire gets the girl in the end. If he looked like Clark Gable it would be pointless, of course. He gets the girl because he can dance! And Hayworth seems more like the equivalent of that Italian guy in Top Hat, Astaire's competition for Rogers in that film, an obstacle to overwin.