By Samir El-Youssef
Halban, £12.99

First, you hope that Israeli Ruth and Palestinian Ibrahim - the displaced lovers of Samir El-Youssef's new novel - will work through their differences and triumph, that their "treaty of love" will symbolise the making of peace in the Middle East. "London is so big," says Ruth, "big enough to make us forget that we belong to hostile people."

Then, chapter by subtly sewn chapter, you are reminded that their cross-cultural challenge is almost superhuman. The hard facts are that Ruth's family home was built on land owned by an Arab and that Ibrahim was born in Shatila camp.

The couple, both in their late 30s, meet at a party in 1993, just after Rabin and Arafat do the impossible and shake hands on the White House lawn. Optimism draws a brief breath.

Ruth is a translator, with eyes that seem "washed with tears", a fugitive from a failed marriage. She was 11 when she lost her war-hero father. Ibrahim is a film-maker manqué who now reviews movies for a small-circulation weekly. He conceals Ruth's existence from his more politically active friends (or thinks he does) and for a while avoids them. How can he remain close to her yet (all too soon) go out celebrating Rabin's assassination with the boys?

El-Youssef's writing is gentle and nuanced, yet it hits hard. He details the idealism upon which Ruth and Ibrahim mean to base their relationship; together, they can perhaps be visionary in their creative fields, create their own peace group. Or even a baby...

United as peace sceptics, he and she try hard to bend their opposing loyalties into understanding. For a time, "each would blame their own lot" when Middle East tensions ran high. But when the suicide bombings begin, they are silenced by difference, and by disloyal desires - hers to revisit Israel, his to seduce the wife of a good friend.

Every couple harbours its own internal strains and fissures but, for Ruth and Ibrahim, current events, history and kinship merge into an exterior demolition squad.

She has a tart, disapproving sister, he has a family secret dark enough to blow the civilised façade off their brave, emotional edifice. It involves rape, disappearance, and dishonour beyond anything Ruth fears.

Such tragedy, both personal and political, leaks the contaminating shame that, El-Youssef suggests, underpins every cruel act in the Middle East.

Born in Rashidia refugee camp, southern Lebanon, this writer knows his ground and, compellingly, stands it. You can see why he holds the Swedish PEN-Tucholsky Award for promoting the cause of peace and free speech in the Middle East. A Treaty of Peace is a masterly piece of filmic fiction, with much to say about the fragility - and force - of shared illusions.

Madeleine Kingsley is a freelance writer