The Man from U.N.C.L.E.

The Man from U.N.C.L.E. was a 1964-1968 American television series about two secret agents who work for the spy agency U.N.C.L.E. (United Network Command for Law and Enforcement). The series starred Robert Vaughn as American agent Napoleon Solo and David McCallum as Soviet agent Illya Kuryakin.

The Her Master's Voice Affair (Season 3, Episode 1)
Solo and Kuryakin investigate a prestigious Long Island boarding school for girls that the daughters of many prominent diplomats and scientists attend. They discover that the school is using subliminal messages to hypnotize and brainwash the students into stealing top-secret information from their parents.