Restless by William Boyd

William Boyd's reputation, won over a career spanning eight novels before this latest, is that of English fiction's master story-teller. Not for Boyd the high linguistic technique of Martin Amis or the elegiac understatement of Ishiguro; he is known, instead, as a maker of richly imagined, and, yes, good, old-fashioned stories. A generator, above all else, of narrative energy.

Previous novels - Any Human Heart, The New Confessions - attest, also, to Boyd's particular concern for the shape and texture of a whole life. Both watermarks of his style are present in Restless. It's the story of Sally Gilmartin, a mild-mannered Oxfordshire widow who, in the hot summer of 1976 reveals her true identity to her daughter; Sally is really Eva Delectorskaya, a Russian émigrée and former WWII spy. This is a novel about our pasts, and the way they never really leave us. A gripping, well-paced narrative is occasionally shaken by bad writing; but that sporadic failure is overcome by the considerable force of Boyd's narrative imagination.

We join Ruth, an Oxford postgraduate and single mother, as she arrives at her mother's house to find Sally Gilmartin surveying the horizon with binoculars. Soon, Sally has pressed a sheaf of typed papers on her daughter. The narrative alternates between Ruth and the incredible story her mother has written; we learn how Sally, real name Eva, left her Russian immigrant family in Paris for dangerous work at the British Security Coordination (BSC) in WWII Belgium and USA. Meanwhile, back in 1976, Ruth ponders this strange revelation and, via her son Jochen's absent father, plays host to German leftist terrorists.

In Ruth and Eva, Boyd has persuasive material; both women are outwardly cynical yet inwardly rent by self-examination, in a way we instantly recognise as truthful. The supporting cast here, though, can seem sketchily drawn. Even the depiction of key figure Lucas Romer, the suave British agent, "swarthy, with dense eyebrows, uncurved", who schools Eva in spycraft, tests Boyd's ability to bring a character to life with a few deft strokes.

Nevertheless, his story circles intelligently around fascinating themes. When a woman can be erased and re-made as Eva is, what relation, if any, do our past selves have to our present? This is a novel made, insistently, from interpretations of individual pasts - Eva on herself, Ruth on Eva - and eminently skilful in its depiction of the way that all human pasts manage a strange trick: to be fixed and always out of reach, yet at the same time, somehow, always with us, and always changing. That comes in the context of Boyd's thoroughly researched depiction of the historically real BSC; we see Eva, in Ostend and New York, join their covert propaganda effort to persuade the USA to enter the war. Research, though, is sometimes rather heavily deployed; Eva casually remembers a friend is leaving, "for London, Electra House, the GC&CS's interception station in the basement of Cable & Wireless's Embankment office".

These are lapses in style, and they extend, also, into Eva and Ruth's interior voices. Boyd makes occasional resort to formulaic constructions: "There was something very odd happening here, I told myself," says Ruth when she first notices her mother's strange behaviour; and later: "Life is very strange, I told myself, you can never be sure of anything." This is laziness from a writer capable of local, as well as global, brilliance. Take Ruth's recollection, for example, of her dying father's mania for turning out lightbulbs, a detail which is Chekhovian in its strange, unsolvable truth.

It's the interest, and insight, of Boyd's overarching story that overwhelms those small complaints. As we learn of the frightening and revelatory end to Eva's career, the two halves of this narrative converge in 1976, and Ruth and Eva together seek closure on the latter's war. It's a final few pages both page-turning and deft, leaving us with a moving feeling that it is our histories, and our ever-changing, private interpretations of them, that render us ultimately unknowable. Restless is that rare thing: a spy thriller from a first-rate narrative intelligence.