In 1953, Nash is invited to the Pentagon to crack encrypted enemy telecommunications, which he manages to decipher mentally. Bored with his regular duties at MIT, including teaching, he is recruited by the mysterious William Parcher of the United States Department of Defense with a classified assignment: to look for hidden patterns in magazines and newspapers to thwart a Soviet plot. Nash becomes increasingly obsessive in his search for these patterns, delivering his results to a secret mailbox, and comes to believe he is being followed.