Mexico Set continues the story that began with Berlin Game, where Bernard Samson's wife Fiona was unmasked as a KGB double agent.

The story begins in Mexico, where Samson is on the trail of his Soviet opposite number: Erich Stinnes, a KGB major working in East Germany whom London Central wishes to coax over to the West.

The task of laying the delicate and elaborate groundwork for Stinnes' defection propels Samson from Mexico to London, Paris, Berlin, and the East-West border.

As he finds himself in a series of ever more incriminating positions, as one by one the avenues of escape or vindication close before him, the novel winds back toward Mexico.. and toward the astonishing climax - at the scene of the defection Samson has so painstakingly orchestrated—in which the allegiances of all involved are finally and fatefully revealed.

Years after its publication, Granada TV made a version of the trilogy for ITV, consisting of twelve 60 minute episodes, called Game, Set and Match, starring Ian Holm as Bernard Samson and Mel Martin as Fiona.