WARNING: The following contains spoilers for Pet Sematary, in theaters now. 

The 1989 adaptation of Pet Sematary, with its screenplay by Stephen King, brought one of the author's most unsettling stories to life, and in the process became a cult classic. However, the new reimagining of the novel is more than willing to explore and expand on the original.

It even makes some major changes to the overarching plot, and radically alters the ending. Here are some of the biggest differences between the new Pet Sematary and the versions that came before.

Rachel's Trauma

In all versions of the story, Rachel Creed (Amy Seimetz) bears the lingering pain and trauma of her sister Zelda's death when she was a child. Zelda was stricken by spinal meningitis, which left her in intense pain and trapped in bed, incapable of leaving her room. She required young Rachel to help care for her, which fostered feelings of resentment.

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But while the earlier versions of Rachel were openly disdainful of her sister, the new incarnation is more traumatized by the experience than enraged. She didn't run away screaming about how fearsome she looked. Instead, Rachel tried to give her dinner using a faulty dumbwaiter. But when the dumbwaiter failed, Zelda accidentally fell in and died. The sounds of Zelda trying to crawl to the dumbwaiter still haunt Rachel, who experiences visions and nightmares for her sister well into adulthood.

Old Man Jud

Jud (John Lithgow) is still the main supporting character after the Creed family moves to Ludlow, Maine. He fulfills much of the same role as he did in the earlier versions of the story, but some slight changes have been made. He doesn't live across the street, but rather next door.  He also forms a better bond with Ellie, playing with her cat Church and removing a bee stinger from her leg (he did that for Gage in the original).

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When he brings Louis to the plot of land where they can revive the dead Church, he's more committed to bringing the cat back to the life because he doesn't think everything becomes demonic. He recounts how he revived his dog as a child, but figured because it was always a mean dog, that's why it came back practically feral. He doesn't tell (or even seem to know) the sad story of Timmy Baterman, a war veteran who was brought back by his father and became a monstrous figure. Instead, that aspect is only referenced during Louis' internet deep-dive to learn the history of the area.

Ellie Dies Instead Of Gage

The defining moment of Pet Sematary in all incarnations is the loss of a child. In the novel and in the 1989 adaptation, it's the toddler Gage who's killed by a fast-moving semi-truck on the road outside the Creed home. But in the new film, it's older child Ellie who dies. While Gage also moves toward the road, Louis is able to save him from the truck.

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But after the demonic Church is set loose and Ellie is told he ran away, the cat returns and waits in the road for her to notice. Ellie moves to catch him, and is killed when a truck loses control and sends a tanker into her. She's buried with no real animosity between Louis and his father-in-law. Their mutual dislike is only ever hinted at in the new film, while previous versions of the story had them embroiled in a fistfight during the funeral for Gage.

Everyone Dies, The End

By killing Ellie instead of Gage, the filmmakers alter how the story plays out. Ellie is more communicative, allowing her to be openly cruel to her targets. That includes Jud, with Ellie appearing as his dead wife Norma when she comes to murder him. Norma was notably absent from both this and the previous film adaptation, although her presence and eventual death is featured in the original novel as a real indicator of death to the Creed family.

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When Ellie attacks her parents, she's able to be more of an outright threat. Instead of killing Rachel suddenly, Ellie stabs her multiple times, and even taunts her as she dies. She drags her mother to the cursed Earth and buries her there, only to be confronted by her father. Louis almost beheads Ellie before being stabbed from behind by his reanimated wife. They drag him to the plot of land as well and resurrect him, leading to the whole family becoming undead figures. The film ends with the three burning down Jed's home and coming to collect the young Gage, with the implication that they're going to kill him and bring him back as well to complete their family.

Directed by Kevin Kölsch and Dennis Widmyer, Pet Sematary stars Jason Clarke, Amy Seimetz, Jeté Laurence, Hugo and Lucas Lavoie, and John Lithgow. The adaptation of the Stephen King novel opens Friday nationwide.