Young Jackie Kernwood, the daughter of the colonel commanding an army post, is bored with the routines of post life, and to break the monotony she organizes a girls' brigade, of which her father disapproves. When the colonel forces her to disband the group, she makes up her mind to run away and become a nurse in the Red Cross. Before she can do that, however, she stumbles across evidence of a spy ring headed by an officer on the post that is plotting to blow up a troop train--and it looks like the chief spy is her boyfriend, Lt. Adair.