In the movie, Linus eagerly anticipates the arrival of the Great Pumpkin, a mythical creature similar to Santa Claus who is said to appear each Halloween night and deliver toys to children who believe in him. His friends, including Charlie Brown, Sally, and Lucy, are skeptical and mock him for his belief. However, Linus remains steadfast in his faith, convinced that the Great Pumpkin will indeed visit him this year.
On Halloween night, while everyone else is out trick-or-treating, Linus and Sally visit a pumpkin patch where he plans to wait for the Great Pumpkin's arrival. Despite the cold and dark, Linus remains confident that the Great Pumpkin will come, even though the night wears on and nobody else believes in him, including Sally who eventually leaves him alone in the pumpkin patch.
Meanwhile, Charlie Brown and his friends engage in Halloween hijinks, with Charlie Brown receiving a rock instead of candy while trick-or-treating. Snoopy also plays a prominent role in the movie, donning different costumes to engage in his own Halloween adventures.
In the end, despite Linus's unwavering faith, the Great Pumpkin fails to appear, leaving him disappointed and disillusioned. However, his friends show him support and encouragement, reminding him of the true meaning of Halloween and the importance of spending time with loved ones. The movie ends on a heartwarming note as the group gathers to enjoy a Halloween party together.