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 U.S. as "Anatomy of Terror."