The untold story of four Jewish American musicians-turned-amateur-spies who risked everything to aid “refuseniks” in the Soviet Union.

In 1985, while the United States engaged in a battle of nuclear brinkmanship, four Americans landed in Moscow on a mission to smuggle secret information in and out using music as their cipher. Under the watchful eye of the KGB, the group faced countless challenges and risks—because they weren’t trained in espionage. In fact, they were musicians with the New England-based Yiddish-music focused Klezmer Conservatory Band (KCB).

Now, the quartet’s saxophonist, Meryl Goldberg, together with Vince Houghton, the Director of the National Security Agency’s National Cryptologic Museum, tell the harrowing story of how Goldberg devised an ingenious plan to encode the intelligence within the group’s sheet music.