After a blood-chilling debut, the Insidious franchise has tried to stay vital by getting viewers thoroughly invested in the struggles of its fan-favourite protagonist Elise Rainier (Lin Shaye) – a challenge, considering that the demonologist/psychic was killed off in the first movie.

Series writer Leigh Whannell, who also appears in the films as the paranormal investigator Specs, kept her “alive” as a spirit in the sequel, and then simply made the next two films prequels.

Yes, The Last Key is a prequel too, and it takes us back even further (not The Further, the phantasmal dimension from which the series’ hauntings emanate) in Elise’s past.

It gives us a glimpse of her haunted childhood and then brings her back as an adult to deal with unresolved, er, daddy issues.

Guess we’ll have to wait a little longer – or maybe forever – to see any sort of exploration or resolution to that cliffhanger-ish ending to Insidious: Chapter 2.

I say “maybe forever” because The Last Key might just be the last straw, too … the one that breaks the franchise’s back.

While it does a decent job of fleshing out Elise’s backstory even more, it bungles the resolution by making it not just predictable, but downright inexplicable, too.

While horror movies do require a certain suspension of disbelief, The Last Key’s deus ex machina ending is simply lazy. In a way, it also demeans the struggles that the main characters endured in the previous films.

The lack of inventiveness shows throughout the film, which relies on standard slow burns and jump scares, with only one bit of misdirection that proved to be effective.

The lengthy opening segment that focuses on Elise’s childhood is the best part of the film, thanks to some effective performances by the actors involved – Josh Stewart and Tessa Ferrer as her parents, Ava Kolker as young Elise and Pierce Pope as her brother Christian – and a creepy, building sense of dread.They manage to infuse this sequence and the characters with a sense of being lived-in, a resigned weariness to the cycle of events that unfolds at the start.

'When you told me this would be a hair-raising experience, I had no idea. Too bad the audience won't feel the same way.' Photo: Sony Pictures

‘When you told me this would be a hair-raising experience, I had no idea. Too bad the audience won’t feel the same way.’ Photo: Sony Pictures

But once the film’s central terror comes to light, so to speak, it’s just a lot of the same old, same old.

Though not all of it feels the same.

Ghost hunters Specs and Tucker (Angus Sampson), who had some pretty funny moments in the earlier films, now come across as just unfunny – and creepy, too.

Shame on you, Elise, for keeping quiet while they shamelessly hit on your nieces. Though ultimately, I guess two creepy admirers are better than a demon sucking out the girls’ life-force.

A pity that this fourth outing misfires so badly. I was looking forward to a few nights of disturbed sleep after watching this. Now I guess I’ll just have to rely on the noisy neighbour upstairs to jolt me awake.

Insidious: The Last Key

Director: Adam Robitel

Cast: Lin Shaye, Leigh Whannell, Angus Sampson, Kirk Acevedo, Josh Stewart, Tessa Ferrer, Caitlin Gerard, Spencer Locke, Bruce Davison