(Major spoilers ahead for “Insidious: The Last Key”)
After four “Insidious” movies, we’ve gone in kind of a circle. The third and fourth films take place before the original — and now the final scene of “The Last Key” brings us right up against that first movie, as Elise (Lin Shaye) receives the fateful phone call that will bring her to help the Lambert family deal with the demonic forces attempting to possess young Dalton’s body.
But that’s not the only reference to the first “Insidious” movie in “The Last Key” — an earlier callback would seem to indicate that the events of this fourth movie actually spurred the plot of “Insidious” into motion.
The big moment comes late in the film, when Elise and her niece Imogen (Caitlin Gerard) are rescuing Imogen’s sister Melissa (Spencer Locke) from the spiritual realm known as the Further. As the trio are attempting to flee the portion of that plane ruled by the “The Last Key” villain Keyface, they enter a red door and find Dalton on the other side, in his bedroom. Not knowing who Dalton was or the significance of the red door, they continue on and successfully save Melissa.
The story in “The Last Key” involves Keyface attempting to harness Elise’s ability to interact with the spirit world in order to gain access to “all the red doors.” Keyface doesn’t succeed, of course, as it’s destroyed by Elise and Imogen at the climax of the movie. But all is perhaps not well, because of that red door they walk through at the end.
I interpreted that moment, when Elise and her nieces encounter Dalton in the Further, to mean that she inadvertently opened the door, literally and metaphorically, for the demons to go after Dalton and generally cause chaos for the Lambert family. Leigh Whannell, the co-creator of the “Insidious” series and writer of all four films, said when I asked him that I was right to read it that way.
“I thought it would be interesting to play upon the idea that Elise herself had some hand in that first film by opening doors and running through,” Whannell said, before elaborating further on what exactly the red doors actually are.
“The doors to me are like literal representations of a metaphysical idea, which is doors between different planes of existence. So we have this plane in this room [referring to the room in which our interview was being held] sitting here on this couch, but then all the other things that have ever happened in this room are kind of overlayed — we just can’t see them. So I see the red doors as sort of opening a door between those two, where things from those other planes can come in.”
The crucial bit of lore added by “The Last Key” being, then, that the doors can’t just be opened by any person or demon — they have to be unlocked somehow, and Elise seems to be able to do just that, ushering in the various demons from the first film when she used that ability.
Whannell explained also that this was a new wrinkle added in “The Last Key,” rather than a reveal they’d been building toward since that original movie.
“It wasn’t something we planned on in the first film,” Whannell said. “In the subsequent writing of the sequels, I’ve had fun playing with this idea of what the Further is and what the red doors represent.”
But if you’re looking for insight into what this new development may mean for the future of the “Insidious” series, you’re going to be stuck speculating for a while, because Whannell hasn’t yet sketched out how this addition series lore will play into future installments.
“I feel like my life would maybe be a lot easier if I pre-planned all this stuff,” Whannell said, “but I never know what I’m gonna do until I get there. I don’t really sit down and think about it until the clock has started ticking on the job.”
And since that clock hasn’t yet started ticking, your guess about where the series will go from here is as good as anyone’s.