Possession (1981)

A young woman left her family for an unspecified reason. The husband determines to find out the truth and starts following his wife. At first, he suspects that a man is involved. But gradually, he finds out more and more strange behaviors and bizarre incidents that indicate something more than a possessed love affair.

Originally passed uncut for cinema. Possession was on the uk video nasties list but wasn't prosecuted! Released uncut in 1999.