London, England

The first chapter of the novel takes place in London, specifically around London's old Tower Bridge. The next couple of chapters take place in another London location, a secret underground center of operations for MI6.

MI6, the CIA

These two organizations are the primary intelligence (i.e. spy) networks in England and the United States, respectively.

The Circle of Cavan

The Circle of Cavan is a secretive counter-intelligence agency interested, as the novel outlines, in accumulating power, money and influence. Its operations extend across international boundaries - in other words, while intelligence agencies like MI6 and the CIA essentially function independently but (mostly) cooperatively, the Circle is essentially a single organization. One of its mysterious goals is to kidnap protagonist Cammie and use her, or the information the Circle believes she has, for some unknown purpose. In other words, the Circle is essentially the book's primary...