Busman's Honeymoon (Lord Peter Wimsey Mysteries)

Lord Peter Wimsey and Harriet Vane marry and go to spend their honeymoon at Talboys, an old farmhouse in Hertfordshire which he has bought her as a present. The honeymoon is intended as a break from their usual routine of solving crimes (him) and writing about them (her), but it turns into a murder investigation when the seller of the house is found dead at the bottom of the cellar steps with severe head injuries. - Wikipedia.