The Avengers S06 E05 Split!

"Mrs Peel, We're Needed!"

When an agent at the Ministry of Top-Secret Information is murdered, Steed and Tara have little difficulty in locating the man responsible. But when a handwriting test indicates that he is Boris Kartovski, someone Steed thought he had killed in Berlin 5 years before, our heroes find themselves drawn into the dangerous experiments of Dr. Constantine.