O'Dell described Sing Down the Moon as a tale of devotion and loyalty. Bright Morning, a young Navajo woman, remains steadfast in her commitment to her family, homeland, and people. The story begins with Bright Morning recalling the first time she led her family's sheep to the mesa at Canyon de Chelly for spring grazing. When a late spring blizzard hits, she shelters the sheep in a grove of trees but becomes scared and flees, abandoning the flock. Although the sheep survive, Bright Morning feels that by leaving them, she has betrayed both the animals and her family. Reflecting on the event a year later and remembering her family's disappointment, Bright Morning realizes the value of loyalty. Her journey throughout the novel—being captured as a slave, enduring the Navajo "long walk" into exile from Canyon de Chelly, marrying the newly crippled Tall Boy, and returning to the canyon with her husband—challenges and strengthens her loyalty to the people and places that define her identity and integrity.