Though The Heavens May Fall by E. V. Thompson
It is 1856. When three men are murdered in Cornwall, Amos Hawke, a Cornish detective working from London's Scotland Yard, is sent to investigate. He finds lodgings with one of the murdered men's wives - and her daughter, Talwyn. But while Amos's relationship with Talwyn gets off to a bad start, she is to prove crucial in helping him bring her father's killers to justice. A wonderful tale from a master storyteller, Though the Heavens May Fall has its heart and soul in the lore and landscape of Cornwall.