Linus and Lucy start the special by going out to get a pumpkin. Lucy insists on a pumpkin as big as Linus, and makes him carry it all the way home. Once home, Lucy cuts it open and takes the insides out. "Oh!" Linus laments. "You didn't tell me you were going to kill it!"
Snoopy helps Charlie Brown rake leaves. Linus is eating a sucker, then jumps in the leaf pile. "Never jump into a pile of leaves with a wet sucker."
"Say, Charlie Brown, I have a football," Lucy tells Charlie Brown. "How about practicing a few place kicks?" Charlie Brown consistently refuses, until Lucy shows him the signed document testifying she won't pull it away. He agrees, and lands flat on his back after she pulls it away. "Peculiar thing about this document, it was never notarized."
"Dear Great Pumpkin, I am looking forward to your arrival on Halloween night," Linus writes. Charlie Brown, Snoopy, Lucy and Patty each come in and mock his beliefs. Sally comes in and is enamored. Linus invites her to sit in the pumpkin patch with him to wait for the Great Pumpkin. "Oh, I'd love to, Linus." Linus mails his letter.
"Hey! I got an invitation to a Halloween party!" exclaims Charlie Brown. Lucy tells him he must have been put on the wrong list. There were two, one to invite and one not to invite. Linus carries a sign out to the pumpkin patch reading, "WELCOME GREAT PUMPKIN."
Sally makes a ghost costume, which scares her. Lucy explains, "A person should always choose a costume that is in direct contrast to her own personality," as she dons her witch mask. More costumed kids arrive. Charlie Brown, whose costume is full of holes, explains he had trouble with the scissors. Snoopy arrives as a World War One Flying Ace. They all leave to go trick-or-treating.
The kids stop at the pumpkin patch to tease Linus. Smitten with love, Sally decides to stay with him. Linus explains that the Great Pumpkin has got to pick his patch, because there's nothing but sincerity as far as the eye can see.
The trick-or-treaters have their nocturnal fun, and compare their goodies after every house. Every time, Charlie Brown gets a rock.
Someone asks about the WWI Flying Ace. Charlie Brown explains his actions--he gets into his Sopwith Camel (which looks strangely like a doghouse) on dawn patrol to shoot down the Red Baron. He gets shot down, then makes his way across the French countryside.
Done with trick-or-treating, the kids stop at the pumpkin patch for more teasing. "He'll be here! You can bet on that!" Sally defends. They leave, and Sally vents her frustrations on Linus, who still insists they'll see him.
At Violet's Halloween party, the girls use Charlie Brown as a model for their jack-o-lantern, drawing a pumpkin face on the back of his head.
The WWI Flying Ace continues his trek across France, pretending to sneak into the window of an abandoned countryside house which is really Violet's, where the party is.
Lucy initiates bobbing for apples, and goes first. Snoopy's mouth is on the other side of the apple she picks. "Blech! My lips touched dog lips! Blech! Uch! Poison dog lips! Blech! Ugh!"
Snoopy goes to Schroeder's piano, and dances merrily to "A Long Way to Tipperary." The song becomes sad. Seeing Snoopy weeping, Schroeder plays a more upbeat song, but then switches to an even sadder one. Overcome with sadness, Snoopy leaves.
Linus and Sally remain in the pumpkin patch. They hear a rustling. "What's that? What's that? I hear the Great Pumpkin! He's rising out of the pumpkin patch!" He faints, and Snoopy, the real "Great Pumpkin", leaves. When Linus comes to, Sally is furious. "I was robbed!" Some other kids are there, and all but Linus leave. Linus calls out, "It won't be long now! If the Great Pumpkin comes, I'll still put in a good word for you! Good Grief! I said 'if'! I meant when he comes! I'm doomed! One little slip like that can cause the Great Pumpkin to pass you by. Oh, Great Pumpkin, where are you!?"
Lucy awakens at 4:00 a.m. She checks Linus's room. It's empty. She goes to the pumpkin patch, where he's shivering, even with his blanket. She brings him home and puts him to bed.
The next day, Linus and Charlie Brown are at the wall discussing their holiday. Charlie Brown says, "I went trick-or-treating, and all I got was a bag full of rocks." Linus sadly admits that the Great Pumpkin never showed up. "Don't take it too hard, Linus. I've done a lot of stupid things in my life," Charlie Brown comforts. "'Stupid'?! What do you mean, 'stupid'?" Linus goes into an angry monologue as the credits roll.