Elise Rainier (Lin Shaye) is a professional medium, and has had her psychic ability ever since she was a little girl (Ava Kolker), but this power did not go down well with her strict father (Josh Stewart) who treated her very harshly, going as far as beating her with a stick to ensure she would stop claiming to see ghosts. This was a futile enforcement of his anger, as no matter how much Elise was struck, the visions went on, and she vowed to help her younger brother at least from whatever dark forces were at work in their haunted home, situated as it was next to a death row prison from where she would derive many of her sightings and sensations. Then one night she was banished to the cellar...
It was all about family in Insidious: The Last Key, although arguably the three previous entries in this horror series were about that too. It was just that we were focused on Elise's family, which didn't extend to offspring of her own, but did include a couple of nieces (Caitlin Gerard and Spencer Locke) who would soon be trapped by whatever entities she had awoken and attracted in her journeys on the astral plane. The fact that she had met a rather unfortunate fate some time before did not prevent writer and star Leigh Whannell from reviving her for every instalment in this franchise, so this was in effect a prequel taking it upon itself to do a lot of filling in of backstory.
Fortunately, Whannell left it light on the exposition with regard to the other efforts, so theoretically you could watch this without having seen the others, presumably what they had in mind as this had been running for the best part of a decade and as it was not one of the must-see series in horror, you had to assume not everyone buying a ticket was going to be aware of the ins and outs of the plot. Indeed, it was kind of surprising Insidious had been so durable since it did not appear to be anyone's favourite chiller franchise, though you could surmise it had enough of a brand recognition that it proved lucrative for Blumhouse to keep on churning them out as long as the writer wished.
He was back as the bespectacled investigator Specs (where do they get these names?) and partnered with Angus Sampson, also back as Tucker and making a humorous double act which had their alliance with Elise more akin to Scooby-Doo, Where are You? They even had a Mystery Machine to drive around in, nicknamed a Winnebaghost here to give you an idea of the level of jokes on offer. Nevertheless, it was not such a terrible idea to apply a little comedy relief, though this was more affable than likely to have you chuckling. What you were really here for was to see Elise re-enter the haunted dimensions and work out what had been plaguing her as a little girl all those decades ago, despite those following the story from before pondering if she was not better to leave well alone.
All that said, it was nice to see veteran character actress Shaye finally land her own successful series in the genre to star in, and she didn't need to put on loads of scary makeup to play some kind of Freddy Kreuger-style villain either, she was resolutely the heroine whose talent for the paranormal and wisdom stemming from it indicated she was worth listening to. Not to accept there were no specifics here that could have done with clearing up, as aside from a not bad twist on the haunted basement where the ghost is not all it's cracked up to be (but is cracking up nonetheless) this was by and large a succession of scenes of the investigators professional and amateur alike skulking and creeping around dusty, musty, cobwebby buildings. Business as usual, then, and with very little variation on what had gone before, family ties or not, The Last Key was pretty familiar stuff that was only lifted by some sympathetic playing from the cast - sympathetic to the material, that was. Music by Joseph Bishara (also much as before).