[1] Set in 1852, it is about a murder on a train which is investigated and ultimately solved by two Scotland Yard detectives, Inspector Robert Colbeck and Sergeant Victor Leeming.

[2] The graphic on the book cover is from T. T. Bury's 1831 depiction called Viaduct across the Sankey Valley in his Liverpool and Manchester Railway series of paintings.

[3] A French railway engineer is killed on a train crossing the Sankey Viaduct and his body is flung over the parapet into the canal below.

Inspector Robert Colbeck, Sergeant Victor Leeming and their former colleague Brendan Mulryne follow the trail to France where they meet Thomas Brassey, whose construction of the Mantes to Caen railway is being sabotaged.

The Detective Department of the Metropolitan Police Force (the Met) was founded in 1842 and so was only ten years old in 1852, when the story is set.