The Unnumbered by Sam North

Illegal, invisible - and invincible - aliens

This odd, hypnotic book about London's "unnumbered" underclass has several real claims to the reader's attention. First, it has one of the creepiest and most loathsome villains I have come across in years, Lucas Tooth. Secondly, it has one of the most attractive heroes, Nio Niopoulos, who manifests a completely believable and un-irritating, kind of goodness. Not many authors can inhabit both extremes of the psychological spectrum with equal confidence.

Thirdly, it tells you about things hardback buyers don't necessarily know: what it is like to be a family of Romanian caravan-dwellers, how to get fake versions of the P45 and identity documents you need to work in a supermarket, and how to con money from lonely women to stay alive. Lucas Tooth has a dismaying number of plausible techniques; reading about him will make you more wary of disguised predators.

Sam North's sixth novel is set among the Londoners whose existence we mostly prefer not to think about, immigrants without proper jobs and roofs, though the capital's drifters are not exclusively from elsewhere. The villainous Tooth is English, as is a selfish middle-class dosser ironically named "Charmer". But the two main protagonists are star-crossed European lovers: the penniless but resourceful Greek installation artist Nio and his 15-year-old Romanian girlfriend, beautiful, volatile Mila, who is grateful to acquire false documents and a job in Tesco. North traces their eager efforts, which he sees as heroic, to better themselves while staying true to each other in a city where everything costs more than they have.

Nio and Lucas are pitted against each other from the outset. In the first pages, Nio is looking down on a motorway when he hears a scream and spots a young Asian woman running from a caravan. Her assailant, though Nio doesn't know it, is Lucas. Symbolically, North is pointing to the vulnerability of illegal immigrants and homeless people to exploitation by the rich world's scavengers.

The vagaries of Nio's and Mila's love-story are tracked and interfered with by Lucas's sinister figure, always immaculately smart, with shirts ironed and pockets filled by one or other of his "sisters" and "mothers": women he meets, gets a hold over, sexually degrades (some of these descriptions are perhaps too protracted) and adds to his crew of victims. Nio, by contrast, treats Mila beautifully, resisting her attempts to get him to have sex with her before her 16th birthday - though, because this is the 21st century rather than the 19th, our hero finally falls.

North kept me reading by the swift, impressionistic, prose with which he inhabits the mind of character after character. There are touches of naivety about some of the invention, but the narrative carried me along. I was happy to take some parts of it as fairy-tale, a counterweight to the forces of darkness. This is an imperfect book, unpredictably skating over important incidents, and its ending feels rushed. But North is a genuinely original writer, and his commemoration of the unnumbered will be hard to forget.

Maggie Gee's latest novel is 'The Flood' (Saqi)