In the summer of 1976, England is reeling, gasping for breath, almost "pole-axed by the unending heat," when Ruth Gilmartin learns that her mother, Sally Gilmartin, was not the person whom she thought she was. Born in Russia, Sally was actually Eva Delectorskaya, a young, attractive Frenchwoman recruited as a British spy during the Second World War.

Living in France, Eva was conscripted by an enigmatic Englishman, a Mr. Lucas Fromer, to work as an undercover agent for the British intelligence services, first in Europe and later in America. But lately, Sally has become convinced that her past may be catching up with her, and a dark current of fear has begun to flow beneath the placid surface of Sally's ordinary life.

After years of a serene existence living in a peaceful Oxfordshire town, Sally has a very real fear that someone is out to kill her. In an effort to alleviate her paranoia, Sally enlists Ruth to help track down the elusive Lucas Fromer, who can perhaps finally put to rest Sally's uncertainties about her past and the deadly game of cat and mouse that she has become caught up in.

Ruth learns that upon the death of Kolia, her mother's brother, Eva (Sally) was enlisted by Fromer to participate in undercover operations in France, before sending her to off England and Scotland where he had her trained in various covert operations as a spy, where the main rule was always to "trust no one."

Eventually transferred to New York, Eva was assigned as an undercover news reporter for the TransOceanic News Agency, where she worked hard alongside the unparalleled British propaganda machine to promote the vital task of persuading America that it was in her interest to join the war in Europe.

While Ruth is left to draw together the fragments of her mother's incredible story, she also has her own cross to bear. A single mother and a teacher of English as a second language, she is forced to confront the attentions of Hamid Kazemi, a stocky, bearded Iranian engineer who hates the Shah of Iran with a special fervor and who has been learning English from Ruth.

When fragments of Eva's own forgotten past begin to surface and the associations become too evident to ignore, Ruth discovers her mother's involvement in a web of duplicity stretching from New Mexico to Canada and all the way back to England.

In this world, British Special Forces and spy networks were bought and sold, and international humiliation was to be avoided at any cost, regardless of the consequences to the lives of loyal individuals. When Eva, however, botches a clandestine operation, a delicate balance is disturbed, and she is forced to take desperate measures to cover her tracks and to muddy the waters.

Author William Boyd presents a deeply compelling account of Eva's story as her journey of wartime espionage eventually catches up with her. Ruth tenaciously pursues any leads she can uncover, determined to hunt down Fromer, partly to assuage her mother's fears and partly to satisfy her own underhanded inclinations.

The tension slowly mounts, and Boyd steers his story towards the inevitable showdown between Eva and Fromer. Meanwhile, Ruth comes to the inevitable conclusion that her mother's life will always be covert and fearful and forever watchful, always "restless," always under surveillance, and suspecting.

The final dénouement is particularly gratifying in a total page-turner that evokes a shadowy world where we all have secrets, and where no one knows even half the truth about anybody else, however close or intimate they may be.