Rest You Merry by Charlotte MacLeod

 Peter Shandy is a tenured professor of agriculture at Balaclava Agricultural College. He likes Christmas and Christmas celebrations as much as the next person, but he hates the College Illumination holiday celebration and year after year refuses to decorate his home to compete with the other houses on the street. Then one year he snaps and orders in decorators to turn his home into a holiday extravaganza, then he leaves town before the neighbors blow a gasket. When he returns he finds Jemima Ames, the wife of his best friend, Tim dead on his living room floor. At first glance it appears Jemima fell and hit her head while trying to rearrange Peter's over the top decorations, But Peter doesn't think so and it's up to him to find out what really happened to Jemima Ames before it happens to someone else.

This is a fun Christmas whodunit. I reread it every year or listen to the audio. It's a good mystery with lots of twists and turns and plenty of quirky characters. The sequels aren't bad, either.