Smiley's People by John le Carré.

Smiley’s People brings to a satisfying conclusion the battle of wits that has been going on between Smiley and Karla for many years. Smiley is called out of retirement to help the Circus investigate the recent murder of a former Soviet army general living in exile in London. The general had been in contact with a Russian woman living in Paris who had recently been approached by Soviet agents with an offer to allow her daughter to leave Russia and move to France. Smiley deduces that the general was assassinated because the old man suspected that Karla was only using the woman’s daughter to create a false identity for some young woman he wanted to send to France. Smiley goes to the European continent to investigate. Smiley appears as a major or minor character in many of le Carré s earlier novels, but Smiley’s People is the first book in which the reader is able to develop a full appreciation of his talents as a secret agent. He is in grave danger because Karla can have people murdered by agents in any country of the world and would certainly eliminate Smiley if he suspected that the British secret service agent was trying to unravel his secret.