1940. Sixteen year old Phillip is one of a number of amateur radio operators across the US, doing it purely as a fun hobby. He is informed by Bill Beck of the Radio and Intelligence Division (RID) of the Federal Communications Commission (FCC) that amateur international radio communication is now banned due to spying a result of the war in Europe. Beck, on behalf of the RID, asks Phillip, however, to continue to monitor the airwaves for suspicious activity. This request is similar to several others made to "Phillip"s across the country by the RID, this group of Phillips the invisible army of unofficial watchers in the name of national security. Their role becomes more important as the US enters the war. The important work of the RID is presented in one case, where they have to locate the source of an enemy radio transmission based on information received from several monitoring stations across the country. The field agents, like Beck, have to do the still dangerous ground work to apprehend the spies, and in some cases take preemptive action in preventing radio contact emanating from US soil to offshore enemies.