The Garden Plot

Description for THE GARDEN PLOT by J S Borthwick:

Much to her dismay, Sarah has been roped into accompanying her abrasive Aunt Julia on a tour of Europe's most famous gardens. The trip, takes a bad turn when the tour's leader, garden expert Ellen Trevino, fails to meet the group for their departure. That and the strange behavior of her fellow tour members plant seeds of suspicion in Sarah's mind. But her bi-continental investigating--with the help of husband Alex at home in Maine--could have Sarah herself pushing up the daisies...

This is #8 in A Sarah Deane and Alex McKenzie Mystery.