Shadows of a Down East Summer (Antique Print Mystery #5)* by Lea Wait.
Maggie Summer is visiting Maine for a few weeks with her significant other Will Brewster. They're staying with his elderly Aunt Nettie at the Brewster family home in the fictional town of Waymouth. Nettie introduces Maggie to Carolyn Chase, a relative of an old friend. She is the daughter of Helen Chase, an artist with whose work Maggie, as a professor of American Studies and an antique print dealer, is very familiar. Carolyn is doing some research into her family's history, and is eager for some advice from Maggie.
At lunch the day after they meet, Carolyn informs Maggie that she's been working on her will, and has left a box full of family papers to Maggie. At first, Maggie is shocked, then honored and pleased, especially when she begins reading the journal of Carolyn's great-grandmother, who was killed in an apparent murder-suicide by her husband.
A few days later, arriving to visit Carolyn, Maggie finds her body lying in the middle of the kitchen with a blood-covered rolling pin nearby, and the house ransacked. Maggie is certain this has something to do with the family papers, though she can't explain why, and as she continues to read the journal, she becomes even more certain. She begins to investigate on her own, and comes under pressure from locals who believe the past should remain in the past.
Wait, who lives in Maine and has been selling antique prints for many years, is very familiar with the story's location and theme, and fictionalizes them wonderfully. The journal entries by Anna May Pratt, a young woman growing up in 1890s East Coast society, are particularly well-crafted.
*FTC Full Disclosure: Many thanks to the publisher, who sent me a copy of the book for review purposes.