The Avengers (1961)

S3E17 The Wringer

Title: The Wringer Plot: Amidst a perilous escape corridor in Hungary and Austria, six operatives have perished. Steed's old companion, Anderson, has vanished as well. Steed manages to locate Anderson, but soon finds himself branded a traitor and captured. He is sent to a brainwashing facility in Scotland, overseen by the notorious Wringer.