In 1947, as the Cold War fires up, the Shield Maidens embark on a mission in Argentina. The Shield Maidens include Erika Lehmann, an infamous spy for Germany during the war; Kathryn Fischer, a former Gestapo officer; and Zhanna Rogova, a notorious Russian assassin. All now work for the newly formed CIA.

The Shield Maidens speak English, German, and Russian, but not Spanish. CIA Deputy Director Leroy Carr is in charge of the Shield Maidens. His wife, Kay Carr, is fluent in Spanish and Kay volunteers to accompany the Shield Maidens to South America to act as their translator, despite having no CIA field training. Leroy Carr agrees only because this would be a run-of-the-mill, very low risk assignment.

The mission would not stay low risk.

When the Shield Maidens go rogue and disappear with Kay, it sends Leroy Carr on a frantic search to locate and save his wife.