It's as if he's been lost in the mists of history.

The known facts are minimal, beyond where and when he was born; his marriage at an early age to an older, already pregnant Anne Hathaway with whom he had three children (who seduced whom?); his move to London, sometime before 1592, to begin his career as an actor and playwright; his son Hamnet, who died, aged 11, in 1596; and his return to Stratford in 1613, where he died three years later.

Few records of his private life remain, although scholars have provided tantalising glimpses.

For instance, Charles Nicholl in The Lodger. Shakespeare on Silver Street (Allen Lane, 2007) revealed the evidence Shakespeare gave at the Court of Records in Westminster in 1612, the only occasion his spoken words are recorded.

The court records also show he had lodgings in the house of a French immigrant family, the Mountjoys, in Cripplegate.

Even less is known about Anne Hathaway, beyond a few references in legal documents.

There is even doubt over her name, as in her father's will she was called Agnes.

It has been speculated that Shakespeare tired of his wife and domestic life in Stratford. There is no evidence to support this, apart from the notorious bequest of the "second best bed" to his wife in his will.

Although he spent most of his married life in London, he did return to his wife when he retired from the theatre.

Germaine Greer in Shakespeare's Wife (Bloomsbury 2007) attempted to rescue Anne Hathaway from obscurity, to reveal the individual who still lives in the shadow of her famous husband, claiming Anne has been consistently undervalued for what she meant to Shakespeare and what she could have contributed to his work.

Maggie O'Farrell, in Hamnet, also attempts to bring Anne Hathaway to life, imagining the kind of woman she might have been and how she would have reacted to the death of her son, Hamnet.

She introduces her novel with an historical note. "In the 1580's, a couple living on Henley Street, Stratford had three children: Susanna, then Hamnet and Judith who were twins. The boy, Hamnet, died in 1596, aged eleven.

Four years or so later, the father wrote a play called Hamlet", leaving the reader in no doubt that this is a story about Shakespeare, even though, throughout the novel, he isn't named.

O'Farrell also decides her Anne will be Agnes. She portrays her as a woman with "a certain notoriety . . . strange, touched, peculiar, perhaps mad . . .[who] wanders the back roads and forests at will, unaccompanied, collecting plants to make dubious potions" and who can read minds by gripping the hand between thumb and first finger.

To her mother-in-law she is an "elf", a "sorceress", a "forest sprite" who has "bewitched and ensnared her boy, lured him into a union".

Hamnet begins in 1596 with 11-year-old Judith falling ill, and her desperate twin searching for an adult to help. But he can find no one. His mother is more than a mile away tending to her bees. His father is in London. His grandmother is out in the town with his sister Susannah, while his grandfather is at the guildhall.

By the time they return, Judith has a high fever, a weak erratic pulse and swellings in her neck and armpits.

Agnes has foreseen her future, and knows that two of her children will stand at her deathbed.

The arrival of twins created doubts in her mind but now she knows that "what she has always dreaded is here".

She knows one of her children will die, but it's not Judith, but Hamnet who dies.

As Agnes battles to save her child, O'Farrell takes her readers back in time, telling the story of her marriage in flashbacks, beginning with the first meeting of Agnes and her husband, as she emerges from the forest near her home with her kestrel, her eyes "almost gold in colour with a deep amber ring around their centre".

She is intrigued as she takes his hand and discovers something unexpected in his mind, "layers and strata, like a landscape . . . a sense too that something was tethering him, holding him back".

The second half of the novel explores the intense grief over the loss of a child and the despair when a frequently absent husband returns for the funeral and then leaves for London again.

She fears she has lost him.

O' Farrell's cleverly conceived climax eventually rescues a novel that tends to wallow in emotion, undermining the strength of a story about sibling love, female strength and the power of words to heal.