In this follow-up to Just Harriet (2022), the protagonist is spending the summer with her grandmother when she finds herself at the center of a mystery. Harriet is staying with Nanu on Marble Island while her father works and her pregnant mother is on bed rest. There is a lot to do at Nanu's Bric-a-Brac bed-and-breakfast, but the best things are all the guests, especially regulars like the Captain, an ornithologist who researches loggerhead shrikes. She has the most pockets and the coolest tools of any grown-up Harriet has ever seen. Unfortunately, the Captain's prized binoculars go missing the same day Harriet has her yard sale. Even more unfortunately, the Captain and Nanu seem to think Harriet may have something to do with their disappearance--and not without reason. Harriet may have had some issues with honesty in the past. As she sets out to find the binoculars and clear her name, Harriet befriends local boy Clarence, who agrees to help her on her quest. Clarence ultimately plays the role of Harriet's moral compass as she learns what it means to be honest and a good friend. Her voice and internal struggle with truth-telling are genuine even if the messaging is heavy-handed. The adult characters also feel a bit flat, and the Marble Island setting is rather bland. Sweet spot art breaks up the text. Harriet reads White; Clarence and his family are Black. A quiet read for those seeking a gentle slice-of-life story. (Fiction. 6-9) Copyright (c) Kirkus Reviews, used with permission.