He's the police inspector who failed to stop a murder, and he can't forget it.

THE WORST MASS MURDER IN NEW ZEALAND HISTORY

In 1866, five men were murdered on the Maungatapu Track near Nelson, New Zealand 

by a merciless gang of ex-convicts from the goldfields of Australia. The gang was after the gold carried by the victims. When the men failed to arrive at their destination, a massive search for bodies was undertaken. Meanwhile, the killers, known as the Burgess gang, were arrested and held in the Nelson gaol until the bodies were discovered in shallow graves. 

A GANG WHO HANGED FOR THEIR CRIMES

With a confession from one of the gang members who turned Queens's Evidence, 

three of the gang members were tried and hanged. But before the murders on the Maungatapu, they had murdered a young surveyor in Greymouth. The leader of the gang, Richard Burgess, gave a deathbed confession, widely seen as an attempt to blame the man who had turned on the gang, that included a description of the death of the surveyor. 

A POLICE INSPECTOR WHO COULDN'T LET IT GO

Inspector William Henry James, an Englishman who had learned his trade in Victoria, Australia, oversaw the Police Camp in Greymouth. Before the murders in Nelson, he knew the gang was in town and forced them to leave. Too late he discovered a murder had already taken place in his town. But one gang member remained in Greymouth, and Inspector James made it his mission to prove that man's guilt and to bring him to justice.