Derby Day at Epsom Downs. A multitude of people crowd to watch the races: dukes and dustmen, bishops and beggars, privileged ladies and prostitutes. The gamut of Victorian society and a hotbed for crime and crooks of all kinds.

With the nation a-flutter in the run up to this national event, a disembodied head is discovered on a passenger train at Crewe; the first in a murky course of events that takes in murder, fraud and race-fixing. Detective Inspector Robert Colbeck and his assistant are assigned to the case and are soon snarled up in a web of skulduggery stretching across the country. They are forced to ask themselves, just how much is someone prepared to hazard to win?