"Miss Nelson Is Missing" is a children's book written by Harry Allard and illustrated by James Marshall. The story follows a kind and gentle teacher, Miss Nelson, who struggles to manage her unruly class. One day, she mysteriously disappears, leaving her students confused and worried. In her absence, the class is taught by the strict and frightening Miss Viola Swamp. The students quickly realize how much they miss Miss Nelson's caring nature and begin to appreciate her teaching style. The story highlights themes of empathy, respect, and the importance of good teachers.