After having strange dreams, Jenny Cole discovers that in her last incarnation she was Mary Sutton, an Irishwoman who died in the 1930s. Suspicious, Jenny goes to Ireland to investigate her past life.

When her doctor recommends that a widow pursue her unfulfilled life ambitions, he doesn't realize that she has always wanted to be a spy. Sending a letter to her congressman gets her an interview with the CIA and accidentally gets her an assignment to Morocco for a supposed easy task of picking up an encrypted code book. When the agency realizes their mistake, they send a super-agent to watch over her. Both are taken prisoner and the real agent is injured, leaving Mrs. Pollifax to use her considerable wits to help them escape and to save the day.

During World War 1, the young Boudreau sisters decide to aid the war effort by catching spies. The strange activities of Nobel-Prize winning scientist Maria Skłodowska-Curie make her a prime suspect. When the girls follow Curie to the battlefront, they witness her fight to use science and her X-ray machine to save the lives of the wounded, including their father.