The Capgras Series

The Capgras delusion (or Capgras syndrome) is a disorder in which a person holds a delusion that a friend, spouse, parent or other close family member has been replaced by an identical-looking impostor. The Capgras delusion is classed as a delusional misidentification syndrome, a class of delusional beliefs that involves the misidentification of people, places, or objects. It can occur in acute, transient, or chronic forms. [ref]