The action of the Russian detective TV series "Cipher" takes place in the late 1950s, in Soviet Russia. The story revolves around former employees of the GRU decryption department: Anya, Sofia, Ira, and Katerina. These women, daring to say goodbye to the peaceful flow of their lives, make the decision to work together again. They create a special group to conduct joint investigations and provide assistance to law enforcement officers. Each case will have a direct connection to one of the heroines.