Based on the Newbery Medal-winning novel of the same name, written by Katherine Applegate and illustrated by Patricia Castelao, the film focuses on a silverback gorilla named Ivan, who lives in a cage in a large shopping mall with an elephant named Stella and a stray dog named Bob. Ivan has no memory of his previous life, and when the baby elephant Ruby arrives, Ivan will be responsible for taking care of her. He also gradually begins to remember his past experiences and makes a plan to escape the cage to prevent Stella from being abused by the administrator. Jolie will voice Stella and Prince will voice Ruby.