"Goodbye, Simon" is a children's book written by James Marshall. The story follows a young boy named Simon who is preparing to say goodbye to his beloved pet, a dog named Buster. The narrative explores themes of friendship, loss, and the emotional journey of letting go. Throughout the book, Simon reflects on the happy moments he shared with Buster, illustrating the bond between them. The story aims to help children understand and cope with the feelings associated with saying goodbye, making it a gentle introduction to the concept of loss and remembrance.