"The fruits of eavesdropping, Mr. Anderson never tires of reminding his disciples, are by nature incoherent rubbish and endlessly frustrating. The patience of Job is not sufficient, in Mr Anderson's judgment, to separate the occasional nugget from the sea of dross in which it swims." This is the voice of Salvo, first-person anti-hero of John Le Carré’s latest mind-tingler.

Le Carré, for those of you who slept out the last century, is the real thing, a writer who was once part of the milieu of which he eloquently speaks. Former operative for M15 (the British equivalent of the CIA), Le Carré posits an underworld spy universe, murky, cold and amoral, in which a few gems of determined purity, such as his great character George Smiley, shine out in contrast. His heroes are rarely handsome James Bond types, are nearly always brilliant and morally conflicted, and often wind up in the soup, unrewarded for their attempts to practice virtue.

Le Carré comes honestly by his view of life as a complex morass where moral principles often add up to less than their stated value. He was born David Cornwell, and his father was a noted scam artist whose machinations broke up his family and drew him to the world of spy versus spy, where secrecy and loyalty are always at odds with the perils of revelation and the consequences of betrayal.

Salvo, like most le Carré protagonists, has elements of the author about him. He is a linguist (Le Carré studied languages) and a spy in training under the tutelage of Anderson, who ultimately sells him out - in a civilized manner of course, as befits an upper-class English government functionary.

Salvo, as he tells us, was born in the Congo of a native mother and a roving European father attempting to live as a priest. Salvo is a “zebra” – blending white and black in a lovely combination that provokes the amorous attention of his priestly mentors as a child and wins him a tasteless English girl reporter for a temporary bride.

Recruited by Anderson to interpret, since obscure African languages are his specialty, Salvo finds himself at a two-day meeting of global importance. He unfortunately eavesdrops on the torture of one of the participants and becomes privy to revelations about the real nature of the summit that force him to try to stop what he considers to be an impending tragedy: "The people will be robbed. Ripped off, as usual."

Salvo wants Anderson to understand the true nature of this perfidy, to side with him as one moral being with another. But Anderson is clinical, precise, phlegmatic: "Torture is a very emotive word, Salvo. I suggest you use it with caution. The word, I mean."

Salvo and his Congolese girlfriend, Hannah, try every means they can think of, using their best amateur spy-craft, to alter the course of events, and we are pulling for them all the way to the end, which is never the end, not really.

Le Carré, who has been quite vocal in recent years about the Iraq War and the American rush to power in the Middle East, uses The Mission Song to imply (not for the first time) a cartel of Western interests (he uses the name Halliburton outright) pulling the strings behind the scenes to wrest control and mineral rewards not only from the despotic rulers in the Congo but from the people themselves. Hardly an unbelievable scenario.