A light in the dark

Rosalind Franklin's reputation rests on her rival's spite. When Jim Watson wrote his racy tale of how he and Francis Crick had worked out the structure of DNA, he indulged himself by slighting most of the other characters in the story. Amid the mockery, Franklin's caricature stood out as "perhaps the most unsympathetic and unattractive account ever given by one scientist of another", in the words of the biologist John Maynard Smith. She stood out in another respect. Unlike the others, she could not answer back, for by the time The Double Helix came out, she was nearly 10 years dead. Cancer killed her in 1958, when she was only 37.

If Watson had not been so crass, she might still be unknown outside science. But Jim the Lad insisted on judging the young crystallographer by her appearance, wondering "how she would look if she took off her glasses and did something novel with her hair". He portrayed her as an uptight bluestocking, too rigid either to work with others or to bring the necessary imagination to the DNA problem, and a wicked witch, jealously hoarding her precious knowledge. Others spoke up in her defence; she became, as Brenda Maddox puts it, "the Sylvia Plath of molecular biology", an indictment of science's institutional sexism.

Because she is dead, the injustice can never be properly redressed, so people keep trying to give the story a fair ending, however awkward. Maddox notes the incongruity in the naming of the Franklin-Wilkins Building, opened by King's College London in 2000, linking the names of a man associated with KCL for 53 years and a woman who was barely tolerated there - least of all by him - for two.

At the same time, there was a lot more to Rosalind Franklin than her unhappy sojourn at Aldwych. It is implicit in the phrase "dark lady", which Maddox appropriates from Franklin's unwilling colleague, Maurice Wilkins. Franklin was guarded, complex, and adept at dividing her life into compartments. Brenda Maddox has the necessary patience, calm and sympathy, though. You can imagine Rosalind confiding in her - and that's saying something.

Maddox is coolly trenchant throughout this outstanding study. She makes a persuasive case that Rosalind's complexity was rooted in her ambiguous social position as an English gentlewoman who was also Jewish. Her class gave her assurance, her ethnicity was a source of unease. Never quite at home in her native land, she went to Paris and lived the Left Bank life, drinking coffee with communists and talking endlessly about ideas, though these concerned science rather than existentialism. Then she came back home, and never knew the same easy companionship and collegiality again. Over here, the old rules applied: she was locked into the petty class antagonisms of English life. One of her complaints against Wilkins was that he was "so middle-class". At Birkbeck College, where she went after King's, she was also considered aloof.

Yet she inspired devotion and love too. Quite how much is a mystery, for her fundamental caution operated in all aspects of her life. She did not make a move before all the pieces were in place. The circumstances with men were never right, so the emotions never found expression. It was certainly nothing to do with her hairstyle. Many people found her quite beautiful - and Maddox assiduously documents her wardrobe, decisively refuting Watson's sneers about not making the best of herself.

Maddox also deals with Watson's claim that Franklin failed to make the best of her intellect. Watson and Crick succeeded by building an accurate model of DNA. Franklin thought the pieces should be in place first: the time to build a model would be when the structure had been determined. Watson and Crick were in a hurry, though, whereas she did not even think she was in a race. She was two steps away, and probably could have got there within a few months. She had clarified a key element of the structure, as well as producing the X-ray image that gave Watson and Crick a vital clue. But even if the boys from Cambridge had been team players, they would never have allowed a girl on their team.