Destination Unknown (St. Martin's Minotaur Mysteries)

Hilary Craven has lost the will to live, Mrs Betterton is already dead. Then Hilary is asked to impersonate the dead woman and to trace her husband - a missing nuclear scientist - and her will to live returns. A faked air disaster, a string of radio-active pearls, a leper colony floundering in the dry heat of the Moroccan desert. Hilary is lead towards a terrifying discovery and her new found enthusiasm for life turns into ice-cold fear...Christie based this book partly on the activities of two famous physicists of the early 1950s: Bruno Ponecorvo, who defected to Russia, and Emil Fuchs, who spied for the Russians. It is another of Christie's light-hearted thriller novels featuring a daring and fearless heroine.