There can be few routes through France which have not been exhaustively charted by travel writers. There's one, however, which runs for fifty kilometres through picturesque-sounding towns like Aubennlhers. Blanc Mesnil and Gif-sur-Yvette. But there are no chateaux here, no charming little totals movers, and absolutely no tourists. Because these are the Paris suburbs, thirty-eight stops on the express subway, the RIR, recalled by most visitors only as a graffitied blur on their way from Roissy airport.

Accompanied by the photographer Anaik Frantz, ex-publisher and novelist Francois Maspero embarked on a tourney of discovery into a terrain vague with ten million inhabitants, a radical past - the 'red suburbs' - and a tense present. The result is this unusual and fascinating book, a vivid mixture of diary, ethnology, history and politics.

At each stop the travellers got off the train, hunted for a room and a meal, and lost themselves in the desolation of billboards. superstores and flyovers. or the uniform comforts of Novotels and solar-heated pavilions. This is a world where names don't make sense, where immigrants from Burkina Faso live in run-down tower blocks called Debussy on the avenue Karl Marx, their kids dodging the police between the Ncee Jules Valles and the Yuri Gagann youth club. A world haunted by memories. glorious and monstrous the Commune, the Popular Front, or the camp at Drancy from where French officials sent a hundred thousand Jews to Auschwitz. A world where no one's a racist but . and National Front posters are everywhere. as menacing as the ubiquitous guard dogs.

Maspero's aim is to put this world back on the map, and he does so with self-effacing humour, genial erudition and unwavering solidarity, helped by Frantz's rare ability to take photos which are both candid and respectful. This is an inspiring record. proof that a month on the RER can teach one more about la France profonde than a year in Provence.