It's the Great Pumpkin, Sam Winchester

It's The Great Pumpkin, Sam Winchester is the 7th episode of Season 4. It aired on October 30th, 2008.

Summary
A witch sacrifices people in a small town to summon a demon who may be a key to freeing Lucifer. To stop her, Castiel brings in an angel named Uriel who intends to destroy the town.

Full Synopsis
The day before Halloween, Sam and Dean are investigating the death of Luke Wallace, who was found having swallowed four razor blades after eating some store-bought candy. Dean discovers a hex bag behind the fridge, but no one can find a reason for a witch to want him dead. In the hex bag, Sam finds gold thread, an herb supposedly extinct for 200 years, a centuries-old Celtic coin, and the charred finger bone of an infant, all indications of an extremely powerful witch at work.

That evening, a high school student drowns in a tub of boiling water at a Halloween party. Her friend, Tracy Davis, tells Sam and Dean that she doesn't know how it happened, and she doesn't know Luke Wallace. Another hex bag turns up in the couch; with some research, Sam concludes that this isn't a grudge at work but a spell, calling for "three blood sacrifices over three days, the last before midnight on the final day of the final harvest." The witch is summoning the demon Samhain on Halloween, the day on the Celtic calendar where the veil between the living and the dead is thinnest. Once Samhain returns, he can raise other things from Hell, which promises a bloodbath if he can't be stopped.

On Halloween day, Dean discovers that Tracy is in fact the Wallace family's babysitter. Sam learns of a violent altercation with one of her teachers, and that she was suspended from school. He and Dean visit Don Harding, the art teacher, whose masks seem to remind Dean of Hell. Don claims Tracy "nearly clawed his eyes out" after he told her her work was "inappropriate and disturbing," describing pages of cryptic symbols and violent drawings in which she participated in horrific killings. No one can locate Tracy to follow up.

The Winchesters return to their hotel room, to find Castiel and Uriel waiting for them. A hex bag was stashed in the wall of the room; the witch is on to the investigation, and they are short on time. Castiel reveals that the raising of Samhain is one of the 66 Seals. He advises Sam and Dean to leave town, because he and Uriel are going to destroy it. Dean refuses to leave short of being killed himself, and Castiel agrees to hold off so the witch can be stopped before she summons the demon. Sam is disappointed by the angels' behavior, but Dean asks him not to lose faith in the cause behind them. "Babe Ruth was a dick," he says, "but baseball's still a beautiful game."

Sam realizes that the infant's bone from the hex bag is too charred to come from a normal fire, and they stop back at the high school art department. The hex bag showed up after confronting the teacher, and they find more children's bones in Don's desk. Meanwhile, Castiel tells Uriel to be patient with the humans: there's a reason they saved Dean from Hell -- he has "potential" and might succeed at this task. Uriel is not convinced, and urges removing Dean and proceeding with the town's destruction. Castiel rebukes him, saying, "You know our true orders."

As trick-or-treaters go about their business, Sam and Dean interrupt Don sacrificing Tracy in his basement. Sam shoots him before he can hurt Tracy -- who reveals herself as a witch, and Don's sister. She incapacitates the boys and completes the spell. Sam smears Don's blood on his and Dean's face; they play dead while Samhain rises, possessing Don's corpse and killing Tracy. They follow the demon to a cemetery, and Dean begs Sam to use Ruby's knife rather than his powers to fight him off. Samhain discovers high schoolers partying in a mausoleum, and locks them inside, where zombies and ghosts attack them. Sam goes after Samhain, while Dean takes on the crypt. Samhain flashes a white light similar to Lilith's but Sam is unaffected. The demon disarms Sam of Ruby's knife, so Sam falls back on his powers, exorcising Samhain at a great physical toll, and in front of his brother.

The next day, as Sam is packing, Uriel appears and warns him not to use his powers again. He threatens Sam with obliteration the moment he stops being useful to the angels. He also suggests the Dean should "get off his high horse," and tells Sam to ask Dean what he remembers from Hell.

Elsewhere, Dean is sitting on a park bench, watching all the children they've saved play. Castiel appears, and reveals the angels' true orders: to do whatever Dean told them to do, as a test of his steadiness under battlefield conditions. Dean, thinking he's failed, asserts that he'd make the same decisions all over again if he had to, because of what he and Sam have saved. Castiel confides that he was praying Dean would choose as he did, and also that he has questions and doubts about the plan from Heaven. He warns that in the coming months, there will be more hard decisions for Dean -- and the angel does not envy him that.

Featured Supernatural Beings

 * Samhain
 * Angels
 * Demons
 * Witches
 * Ghosts
 * Zombies

Featured Music

 * "Just As Through With You" by Nine Days (playing at the Halloween house party)
 * "Bomb" by Triple 7 (playing at the Halloween crypt party)

Continuity

 * Uriel is introduced, as is one of the angels' slurs for humans: "mud-monkey".

Trivia

 * The aliases "Agent Geddy" and "Agent Lee" are a reference to Geddy Lee, who is the lead vocalist, bassist, and keyboardist for the Canadian rock band Rush.
 * The alias Dean gives after the second death scene is "Agent Seger" which is a reference to classic rock icon Bob Seger.
 * The art seen as Sam explains the lore surrounding Samhain is reminiscent of Gustave Dorés illustration in Inferno, Divine Comedy by Dante Alighieri.

Quotes
         Dean: This Luke Wallace--he was so vanilla that he made vanilla seem spicy.          Uriel: We're wasting time with these mud monkeys.
 * Sam: What about you? Find anything on the victim?
 * Sam: We'll stop this witch before she summons anyone. Your seal won't be broken and no one has to die.
 * Dean: (while fighting a zombie) Bring it on, stinky!


 * Dean: Zombie-ghost orgy, huh? Well, that's it. I'm torching everybody.

        Uriel: By a mud monkey.
 * Castiel: The decision's been made.

Castiel: You shouldn't call them that.

       Uriel: Oh, that's what they are... savages. Just plumbing on two legs.

       Castiel: You're close to blasphemy.