Book 21 of the Aunt Dimity series (series numeration from Goodreads.com).
While exploring the attic in her cottage near the small English village of Finch, Lori Shepherd makes an extraordinary discovery: a gleaming gold and garnet bracelet that had once belonged to Aunt Dimity. When Lori shows the garnet bracelet to Aunt Dimity, it awakens poignant memories of a doomed romance in Aunt Dimity’s youth in London after the War. Regretfully, Aunt Dimity asks Lori to do what she could not: return the bracelet to her unsuccessful suitor—setting Lori off on an adventure through London—and through history—to put a piece of Aunt Dimity’s past to rest. In the meantime, a new family has moved to Finch. The villagers are thrilled because their new neighbors are avid metal detectorists. Metal detectors soon become all the rage in Finch and the villagers unearth a lot of rubbish (some of it quite embarrassing) before one of them stumbles upon a trinket that could hold the key to the origin of Aunt Dimity’s bracelet. Is the bracelet a priceless and protected national treasure? Was Aunt Dimity’s lovesick suitor a common thief? If so, how will Lori break the news to Aunt Dimity? And what will she do with the bracelet? As Lori searches for answers, she discovers an unexpected link between the buried treasure in the village and the treasure buried in Aunt Dimity’s heart.