The Man Next Door (DI Thomas Maitland 2)

Retired police detective inspector Thomas Maitland has rented a house in Cornwall; he's going to paint his way to recovery from the experiences of the spring. A local woman with an intriguingly expensive collection of modern art wants to put on a show of his work.
But Maitland's next door neighbour, also his landlord, is unsettling, and when he finds his benefactor dead at the bottom of her garden, Thomas Maitland feels death casting its net over him again.