Fourteen year old Harriet is a girl who doesn't quite fit in, and when she's kicked out of the Girl Guides for fighting, her father doesn't know what to do with her. As war breaks out and the Scouts and Guides are volunteered to support the war effort at home, Harriet decides to form her own army of misfits, mounting their own patrols to track down German spies. Soon, she and her army become embroiled in a daring adventure on the hunt for an enemy who is much closer to home than they realise.