What if the great thinker's lost daughter had lived? Marina Benjamin on fiction after the facts; Mrs Einstein by Anna McGrail Doubleday, pounds 15.99
Anna McGrail's second novel appears to be named for Mileva Marle, the Serbian science student with whom Albert Einstein fell in love whilst working for his degree at Zurich and later married. But it isn't. Mrs Einstein is named for Lieserl, the illegitimate daughter Mileva bore Albert in shame and secrecy in 1902.

Lieserl has been entirely erased from history. There are no official documents attesting to her existence, no mentions in memoirs and scarcely any reliable gossip. The only hard evidence that she ever came into the world comes from letters between Albert and Mileva uncovered in 1986 by scholars working on the Einstein papers project. Einstein enthused, "I love her so much and I don't even know her yet," but it seems that he never set eyes on the girl. She may have been given up for adoption. Most likely, she died from the scarlet fever she contracted in 1903. Then again - and this is McGrail's inspiration - it is just possible that she survived.

McGrail has taken this real-life Anastasia and made of her a mathematical genius. By the age of 17, she has not only mastered Newton but discovered for herself the theory of relativity. Leaving her father in the slow lane, she dispenses with the cosmological constant he had insisted on using because he refused to accept that the universe was expanding or contracting. Then, in a move calculated to please scientific trainspotters, she makes Lise Meitner's discovery that a uranium atom may be split clean in two.

If this novel were merely some sort of Shakespeare's-sister exercise in the recovery of lost women, one might want to take issue with Lieserl's implausibility: she is a walking compendium of 20th-century theoretical physics, after all. But its proper context is not so much history as myth. McGrail's Lieserl is a monster, a demented prodigy bent on using science to avenge herself against the parent who turned his back on her; a Frankenstein, if you will.

Thus her moment of triumph comes when, having infiltrated the Manhattan Project, Lieserl abets the making of the atom bomb. Only when the world sees the brilliant dawn of a nuclear sun, she reasons, will it know the real meaning of her father's equation of mass with energy. Of course, her torment, like that of Mary Shelley's creature, cannot end until she confronts her maker and learns that her murderous inclinations are no more than a mask for her pain.

It is a brave writer who puts theoretical physics at the centre of a novel. But if McGrail's valiant effort to use science as a plotting device ultimately lacks persuasiveness, it is largely because stories do not move forward in the same way that science does, through problem-solving. By binding Lieserl's emotional momentum to the laboratory, McGrail hampers her own attempts to create a multi-dimensional character. That said, she has found an ingenious way of circumventing this problem by deliberately flattening Lieserl still further.

Her Lieserl is effectively a ghost, moving undetected through the scientific world of the 20th century, tinkering quietly and remaining invisible. Her business is to haunt - ostensibly her father, but more generally, the conscience of modern science. In effect, Mrs Einstein is a strange kind of counterfactual history, one that fails to tell you how things might have been otherwise.

Lieserl lives in between recorded fact and lived lives; her existence changes nothing. As a novel about self-erasure, Mrs Einstein sits as far away from the programme of recovering lost women as possible, suggesting perhaps that it is time to rethink the principles of feminist demonstration.