The Poisonings of Horpington

Detective Harry Sergeant must find out why people are dying in his town. What Harry doesn't know is that two young women are also hunting for the perpetrators, who killed their relatives several years earlier.
But what can two young women do against the perpetrators that Harry can't?
In a victorian-esk world this story has a mildly steampunk feel, with steam engines, horses and the device.