It's 1949 and the Deep South is experiencing a summer longer and hotter than anyone can remember. Summer refuses to leave. It's Autumn's job to get rid of Summer and start things moving for the fall. In the process, she comes to know almost-13-year-old Billy Burnette and his dog Punchy, who live with Billy's grandfather, Pap, near the Gulf of Mexico. Pap is worried about money and is drinking too much. He has a chance to make a large sum by selling a strip of his land. The problem is, there's a magnolia tree on the strip that has been declared the largest in the state and is protected by law. The developer wants to clear the woods completely to build a string of cabins, but the tree must be removed before he will buy the land. Pap hires two men to kill the tree. The big tree is Billy's refuge. Can Billy and his friend, Rick, find a way to save it?