An Echo of Theresa (1973)

American businessman Brad Hunter and his wife Suzy are visiting England for the first time Meeting a business contact Brad introduces his wife as Theresa But it seems to be more than an innocent slip of the tongue Brad begins behaving strangely and knows more about specific locations in London than he would as a first time visitor Suzy hires private detective Matthew Earp to look into the reasons behind her husbands sudden change in personality This aired on British TV as part of the Thriller series under the title An Echo of Theresa but was issued as a featured on home video in the US as Anatomy of Terror