It's 1979, and Downing Street is about to be occupied by a very new broom (or a nasty old stick, depending on your point of view). Someone's got to keep the unions in their place, so British Intelligence can expect good treatment, but only if it cleans its own house. Roy Nichols is informed that one of his team is a traitor, and is ordered to find out which one. Nichols' team consists of only two people, and therein lies the problem - with only two official suspects and only four major characters, both turns of the double twist at the end are a bit too easy to anticipate. That aside, this story has plenty of virtues: the characters are vivid and crisply drawn, and the style is often a delight, particularly the evocation of one briefly-glimpsed slattern's hair colour.