It's the night of Peppermint Patty’s New Year’s Eve bash, but Charlie Brown has to write a book report about War and Peace. Hoping to join the fun for a special dance with the Little Red-Haired Girl, he tries desperately to finish in time.

Cass Brown is about to marry for the second time; his first marriage, to Isabel was annulled. But when he discovers that Isabel just had their baby, Cass kidnaps the infant to keep her from being adopted. Isabel's parents hunt for the child and discover that Cass and Isabel are still hopelessly in love.