Riley Oh is a Korean-American adoptee who feels like an outsider in her magical family, the gifted Gom clan. When she and her sister Hattie attempt a dangerous spell to share Hattie's healing magic, they accidentally trigger a curse that threatens Hattie's life. To save her, Riley embarks on a perilous quest through the magical underworld of Los Angeles to find the last fallen star—a powerful celestial object that might be their only hope. Along the way, Riley discovers shocking truths about her own origins and must decide what truly makes a family.