Just after midnight on October 4, 1922, Edith and Percy Thompson were walking along a street in the London suburb of Ilford when a man set upon Percy, stabbing him four times and killing him.

A 20-year-old ship's steward, Fred Bywaters, was arrested for the murder.

So was the 34-year-old widow, Edith Thompson, who, it transpired, was Bywater's lover. The subsequent trial galvanised the British public, much to the mystification of the press who covered it, who reckoned there were no circumstances in the case to evoke the slightest sympathy. The crime was premeditated and long contemplated - the whole case was simple and sordid.

Yet the reason the public was fascinated, and signed a petition in its thousands in support of Edith Thompson's application for a pardon, was that it wasn't as simple as the jaded court reporters supposed.

While nothing could save Bywaters, who wielded the knife, poor Edie was convicted on the strength of a clutch of love letters she wrote to Freddy.

It's not hard at all to see why the attention of the public was captured and held: the letters told a tragic love story at the same time as they aired the dirty laundry of an unhappy marriage; in an age which insisted upon an impossible standard of sexual propriety in women, they were breathtakingly candid about female sexual desire.

The prosecution built its case out of one interpretation of apparently incriminating passages contained in these letters. But there was an alternative sense to be gleaned, and this forms the basis of Jill Dawson's latest novel.

Working from the letters and contemporary news reports, Dawson interpolates. The novel purports to be a series of letters written from Edie in her prison cell to Fred in his. They are never sent, and in reality serve as a kind of a diary for poor Edie, reflecting upon her life, her childhood, her marriage to Percy, her affair with Freddy, the crime itself. She seeks the moment in the game of life's hopscotch where she might have thrown the chalk in a different direction, hopped into a different square, moved toward a different destiny.

The novel constructs Edie as free spirit in an age of conformity, which stressed duty above happiness, particularly for women. She is foolish, and recognises her folly too late.

As far as Edie is concerned, it is a brilliant feat of characterisation, and it is equally adept at evoking the claustrophobic age in which she lived.

It's hard to say whether less care has been taken to draw Fred - he never quite comes alive - or whether this is simply consistency in point of view: if Dawson's theory of the case is correct, then Edie never understood her fiery young lover at all. Either way, it's a trifling criticism. This is a dazzling novel, gripping and moving. It reminds the reader of how far we have come as a society, at the same time as it raises awareness of unsettling resonances.

* John McCrystal is an Auckland freelance writer.