Busting foreign spies on domestic soil. Cracking the code on drug and human trafficking. Shutting down the mob. They are the elite Cryptanalysis Unit of the Federal Bureau of Investigation, examining manually encrypted documents and records of illegal enterprises, providing expert testimony, forensic assistance, and identification of terrorism, foreign intelligence, and criminal activities in support of federal, state, local, and international law enforcement investigations and prosecutions… Ciphers. Codes. Encryption. Passwords. Meet the best of the best at puzzling out the truth and protecting all of us from those that would steal information in ways that can shatter the global community and kill. But what happens to the Cryptanalysis unit when one of their own goes missing?