Miss Jackie of the Army 1917

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.