The Avengers (1961)

S3E12 Don't Look Behind You

Cathy is invited to enjoy a weekend at the residence of Sir Cavalier Resagne, a specialist in medieval costumes. However, she soon finds herself alone in the house, being harassed by a young man who insists he is a film director, while also grappling with memories from her past. Meanwhile, Steed's whereabouts remain a mystery.