The Sleeping Voice, by Dulce Chacón, trans Nick Caistor

You might think, as we enter the 70th year since the outbreak of the Spanish Civil War, that Spaniards would start to forget the conflict that tore them apart, and let the scars heal. Survivors are very elderly, their middle-aged children - who became adults during Spain's democratic rebirth - remember little, and their grandchildren may barely have heard of Francisco Franco.

Many Spaniards want to forget; they urge their compatriots to reconcile old rivalries, look ahead and stop raking over the coals of an extinguished conflict. They bat away as tiresome and provocative those seeking justice for Franco's victims.

Why not dig up mass graves of the dictator's anonymous victims? I once asked Ana Botella, a Madrid city councillor and wife of Spain's former conservative prime minister, José Maria Aznar. "It's not worth wasting our energy," she replied, offering a rare glimpse into the mindset of conservative Spain.

There were atrocities on both sides, many say. Feuds scythed through families, silencing political discussion at the dinner table, freezing dissenters out of the family circle. Enough, they say, let's forgive and forget. But there are two Spains. The country was divided during the civil war, during the republic it destroyed, during the dictatorship that followed and during today's sturdy democracy, where the split is reflected in voting patterns.

For half the nation the wounds of the civil war never healed. Franco's victory brought not peace but the prolongation of war through 40 years of dictatorship. "With the red army captured and disarmed," began Franco's vengeful declaration of victory in 1939. The losers suffered humiliation and persecution decades after they had surrendered. They kept mum after Franco's death in 1975 to ease the transition to democracy. But they cannot forget.

Dulce Chacón's The Sleeping Voice tells of the women who lost the war: female prisoners who suffered the vilest atrocities of Spain's most miserable epoch, and were forced to remain silent. Their silence - their sleeping voice - is only now ending. Chacón's novel was a huge success when it appeared in Spain; it was based on testimonies of women she had spent years tracking down. She came upon a hidden sisterhood - proud, unrepentent, but still afraid.

In a report she wrote for El Pais, Chacón recounted how, on a stifling August day, one of her interviewees, in her eighties, closed the window for fear her confession might be overheard. She spoke only in a whisper.

She said she was detained as a girl because she was stitching a Republican flag near the window and someone saw her. Another spoke of being forced to kneel on chickpeas until her knees bled. Expressing the anguish of wasted years, one says that when her two children visited her in jail, they failed to recognise their mother. Another discovers after years of imprisonment, with three months left to serve and a husband waiting, that she can never have children.

The novel starts in 1939 and tells of a group of women held in Madrid's Ventas prison for having backed the losing Republicans. They are cold, hungry and subjected to random cruelty for trivial misdemeanours, never knowing when they will be taken for trial, or to be shot.

Hortensia is pregnant, and the authorities wait only for the child to be born before executing her. She is accused of "joining a rebellion" - as if "the nationalists were not the rebels against the elected republic". Her husband Felipe fled to the hills to support a guerrilla struggle that collapsed in the late 1940s, when it was clear no European democracy would help free Spain from dictatorship.

Elvirita, 16, had waited among tens of thousands in Alicante for ships to carry Republicans to safety. The ships never came, and she was seized by Falangists. Tomasa watched her husband and four children tossed from a bridge, shot as they struggled for the river bank.

And blue-eyed Pepita, timid and apolitical, is the link with the outside world. She lives in the house of Doña Celia, whose daughter was shot. Pepita brings her sister food, clothes and news. She passes a message to Felipe, and falls in love with his comrade Paulino. Paulino is jailed; and she waits for him 17 years. When he is amnestied and they marry, the couple remain under constant police surveillance. Pepita's is a true story.

Dulce Chacón is neither sentimental nor melodramatic. Her voice is spare and gentle. But, after reading without stopping the accumulated detail of casual sadism, desperate whispered conversations, stifled grief, flashes of love and bliss, I found my jaws were clenched. Chacón, who died in 2003 after this book's publication from cancer, aged 49, came from an aristocratic, right-wing family, albeit a civilised one.

"I grew up hearing only one version of the war," she said. "I knew there was another side to the story." Her narrative is fictional, but the events are real. Some are even softened versions of incidents the author thought too brutal for the novel.

Spain's ruling socialists are now trying to bring justice to Franco's victims. They have compensated, sometimes only symbolically, those long punished for being Republicans, driven into exile, or imprisoned for crimes that amounted only to dissent. But shadows of the dictator remain. Street names still honour Fascist generals and regiments. When statues of the Caudillo were removed from Spanish squares just months ago, screams of protest came from those who accused the authorities of "opening old wounds".

Those wounds never closed. In villages throughout Spain, neighbours still look askance at each other because of what they or their parents did in the war. Most Spaniards I know have confided some horror that blighted their family for three generations, often revealed only recently as grandparents dared to break their silence. More people are speaking out; campaigns, novels, histories, even plays and art shows now examine the human costs of the war, and the concentration camps, forced labour, broken families, unmarked graves and decades of self-censorship that followed. Meanwhile a thriving pro-Franco industry, probably driven partly by fear and guilt, embellishes the Caudillo's image and lauds his achievements.

Spain has not come to terms with its past. Antagonists still call each other rojillos (reds) or fachas (fascists) - insults virtually extinct elsewhere in Europe. It has not made gestures of reconciliation that even Argentina and Chile - whose dictators ruled four decades after Spain's - are attempting. Spaniards remain burdened by the pain and shame of their memories.

Elizabeth Nash's cultural and literary history of Seville is published by Signal