Patrice des Moutis was a handsome, charming and well educated Frenchman with an aristocratic family, a respectable insurance business, and a warm welcome in the smartest Parisian salons. He was also a compulsive gambler and illegal bookie.

Between the late 1950s and the early 1970s, des Moutis made a daring attempt to beat the French state-run betting system. With a genius for mathematics and a deep love and understanding of the horse-racing world – not to mention excellent relationships with all the top trainers and jockeys – he applied himself to his task with vigour and meticulous research. A series of spectacular coups netted him (and his friends, with whom he generously shared his predictions) the equivalent of millions of pounds, and soon saw him nicknamed Monsieur X and hailed as a hero by a public desperate to see someone get one over on the state.

Des Moutis' success so alarmed the authorities that they repeatedly changed the rules of betting in an effort to stop him. And so a battle of wills began, all played out on the front pages of the daily newspapers as the general public willed des Moutis on to ever greater successes. He remained one step ahead of the authorities until finally the government criminalised his activities, driving him into the arms of the underworld. Eventually the net began to close, high-profile characters found themselves the target of the state's investigation, and people began turning up dead.

This long-running cat and mouse game – with the law on one side and des Moutis and the gangsters on the other – is a dazzling tale of glamour, riches, violence and ultimately tragedy.