Halloween is upon us! That means fans of the ghoulish holiday should start unpacking their spooky decorations, carving up their jack-o-lanterns and begin preparing for a slew of celebratory specials to hit the small screen -- like the 1966 animated classic “It’s The Great Pumpkin, Charlie Brown.”

The annually aired, holiday-themed special, created by Charles M. Schulz, will air on ABC on Tuesday, Oct. 20, and Thursday, Oct. 29, at 8 p.m. EDT. So make sure you mark you calendars so you don’t miss out on the Halloween fun!

The Emmy-nominated series begins with the Peanuts gang preparing for Halloween. But while Charlie Brown, Lucy and the others anticipate a candy-filled night of trick or treating, Linus, Lucy's younger brother, writes his annual letter to The Great Pumpkin -- an act that confuses his best bud Charlie Brown.

“On Halloween night, The Great Pumpkin rises out of his pumpkin patch and flies through the air with his bag of toys for all the children,” Linus explains to his befuddled friend.

But despite Linus’ explanation, Charlie Brown thinks that The Great Pumpkin is a “crazy” concept.

“When are you going to stop believing in something that isn’t true?” he says to Linus, only to have his blanket-loving friend bark back that he’ll stop believing in The Great Pumpkin when Charlie Brown stops believing in Santa.

The rest of the 30-minute installment follows Linus’ story line as he waits for the arrival of his holiday hero. He even convinces Sally, Charlie Brown’s little sister, to ditch getting candy (or in Charlie Brown’s case, rocks) so the two can experience The Great Pumpkin’s debut together.

It’s The Great Pumpkin, Charlie Brown 2015 abc Linus and Sally spot Snoopy in the pumpkin patch during the holiday classic "It’s The Great Pumpkin, Charlie Brown," which will air on Tuesday, Oct. 20, and Thursday, Oct. 29, on ABC. Photo: ABC

But when Snoopy shows up instead of Linus’ Halloween guest, Sally gets upset and blames Linus for making her miss out on trick-or-treating and Violet’s Halloween party. She leaves Linus in the pumpkin patch alone to wait for The Great Pumpkin’s grand arrival.

However, when the clock strikes 4 a.m. the next morning, Lucy notices her brother isn’t in his bed. She makes her way to the pumpkin patch to find Linus shivering in his sleep. So she brings him home and puts him to sleep, only to have Linus wake up sorely disappointed -- especially when Charlie Brown says to Linus that he, too, has done “stupid” things in his life (insinuating that waiting for The Great Pumpkin wasn't such a great idea).

This sets Linus off on a rant about how next Halloween he’ll find an even more “sincere” pumpkin patch to wait in so that The Great Pumpkin will reveal its magical self.

“It’s The Great Pumpkin, Charlie Brown” will air Tuesday, Oct. 20, and Thursday, Oct. 29, at 8 p.m. EDT on ABC.