Donnelly combines a mystery with a coming-of-age story about a girl choosing among family obligations, romance, and education. The mystery derives from a true event, the death in 1906 of a young woman in northern New York. In this fictional rendition, 16-year-old farm girl Mattie Gokey is working for the summer at the hotel where the murdered woman has been staying and has given Mattie letters to burn. As the details emerge about the possible murder, Mattie struggles with whether to burn the letters or turn them over to the police. She also wrestles with a deathbed promise to her mother to stay and raise her younger siblings. Mattie, who loves language and excels at creative writing, longs to go to New York City for college, encouraged by a feminist schoolteacher. The story’s structure reflects the two promises at issue, with chapters narrated in present tense set at the hotel during the summer and chapters in past tense set during the preceding year when her mother died. The chapters from the past take their headings from new words Mattie is learning from her dictionary, a device that grows a bit tedious, as do the myriad details about the farming life. Issues about racism and women’s rights are more deftly woven into the action. While tighter writing would have enhanced the work, this is nevertheless an absorbing story that will appeal strongly to the growing number of historical fiction fans. (Historical fiction. 12+)