Death of a Travelling Man by M.C. Beaton

It's springtime in the Highlands but storms are brewing for Hamish Macbeth. His life is going to pot. He has - horrors! - been promoted, his new boss is a dunce, and a sinister self-proclaimed gypsy and his girlfriend have parked their rusty eyesore of a van in the middle of the village.
Hamish smells trouble and as usual he's right. The doctor's drugs have gone missing. Money vanishes. And neighbours suddenly become unneighbourly. Nobody wants to talk either, so canny Hamish faces the delicate task of worming the facts out of the villagers.
In the process he uncovers a story so bizarre that neither he nor the locals may ever be able to forget it...