When the Cookie Crumbles is the third in the Cookie Cutter Shop Mystery series by author Virginia Lowell.  The first book was Cookie Dough or Die and the second was A Cookie Before Dying.

Synopsis:

Olivia Greyson is the proud owner of The Gingerbread House—a quaint shop that specializes in all things cookie—and her best friend, Maddie, is her sidekick, baking up scrumptious treats for their parties. But the real-life version of their magnificent gingerbread house is about to crumble to pieces…

Tensions are running high as Chatterley Heights’ 250th birthday celebration approaches, and Olivia and Maddie are working feverishly to finish a gingerbread house modeled after the famous Chatterley Mansion. When Paine Chatterley, presumed to be dead, shows up to claim his father’s house, the town gossips are driven into a tizzy. And when he refuses to allow visitors to tour the mansion during the celebration, all the preparations seem for naught.

Then Paine is found lifeless in the bathtub, his wife hysterical and their precious heirlooms destroyed. The hidden lives of the prestigious Chatterley family members begin to surface, and Olivia must unravel their dark past. As it turns out, the town’s history isn’t all that sweet…