Frank Close used to be a research physicist who wrote rather good books on the side. Latterly, his research activity has declined and he has devoted rather more time to writing even better books. On the evidence of Half-Life, which is undoubtedly his best book so far, it is a pity for us that he did not give up the day job sooner. No longer a physicist who writes, he is now a writer with a background in physics, in the same way that after ‘retiring’ Dick Francis became a writer with a background in horse racing.

Indeed, the story told here, of the divided life of the Italian physicist Bruno Pontecorvo, could have formed the basis of a Dick Francis-type action thriller, or a John le Carré spy story with added science. For the first half of his life, up until