"The One and Only Ivan" is a novel by Katherine Applegate. Ivan is a silverback gorilla who lives in a stationary circus. Ivan is good friends with the other animals in the circus, especially Stella the elephant and Bob, a stray dog. When Stella dies, Ivan makes a promise to save her young friend, Ruby, from a life of captivity. It takes some time, but Ivan and Ruby are eventually moved to a zoo. "The One and Only Ivan" is a book of great courage and hope.