“INSIDIOUS: THE LAST KEY” — 3 stars — Lin Shaye, Leigh Whannell, Angus Sampson, Spencer Locke, Tessa Ferrer; PG-13 (disturbing thematic content, violence and terror and brief strong language); in general release

“Insidious: The Last Key” is the fourth film in James Wan’s horror franchise and technically the sequel to a prequel, but don’t worry. If by chance “Last Key” is your first Insidious film or, if like a certain film critic who shall remain nameless, you had to double-check IMDB to remember what happened in the previous installments, this latest effort won’t leave you too far behind.

The films all have a simple premise: Elise (Lin Shaye), a 60-something ghostbuster with a gift for communicating with the dead, helps troubled families to evict the demons that are tormenting them, usually by crossing over into a supernatural void called The Further. For some mild comic relief, Elise’s assistants Specs (Leigh Whannell, who also wrote the film’s script) and Tucker (Angus Sampson) usually tag along for the paranormal ride.

In the first two films, Elise was working with the Lambert family, and in 2015’s “Insidious: Chapter 3,” we went back to see how Elise got her start in the business. Adam Robitel’s “Last Key” takes place in the aftermath of “Chapter 3,” as Elise has to return to the house where she grew up to confront some familiar demons.

Elise is careful to use the term “house” instead of “home.” In the flashback that opens the film, we see Elise as a young girl (played by Ava Kolker) in New Mexico. She and her younger brother Christian (Pierce Pope) live under the abusive hand of their father Gerald (Josh Stewart), who refuses to believe in Elise’s supernatural gift and, as she puts it later in the film, tries to beat it out of her. On one particularly bad evening, Elise is locked in the cellar, where she winds up unleashing an especially nasty demon in an episode that costs her mother (Tessa Ferrer) her life.

Fast-forward to 2010, and Elise gets a call from a man named Ted Garza (Kirk Acevedo) who just happens to live in her childhood home. After some hesitation, she packs up Specs and Tucker and sets out for Five Keys, New Mexico, which looks about six months shy of officially becoming a ghost town.

Here, Elise sets about expunging the demon that is keeping Garza up at night — only you know it isn’t going to be that simple. She also has to confront her brother (Bruce Davison) who still lives in town, along with his daughters Imogen (Caitlin Gerard) and Melissa (Spencer Locke).

Fortunately for the audience, an early heavy reliance on jump scares eventually settles into a pretty solid and creepy narrative that uncovers demons from Elise’s past of which she was completely unaware. (Sensitive viewers should note: Though “Last Key” stays in PG-13 territory, its subject matter gets pretty dark the more we learn about the nature of those demons.)

Whannell's script gives us a few fun twists and turns that keep “Last Key” from merely going through the motions, and for the fourth film in a franchise, it does a good job of keeping things interesting.

Without spoiling anything, the third act does flounder a bit, and since you know the film is a prequel — or at least the sequel to a prequel — there’s only so much genuine tension you can mine from a situation where you already know the principal characters are going to make it through unscathed.

But for a horror release in January, “Last Key” packs enough fun and scary moments — keep an eye out for the suitcase sequence — to keep audiences engaged. Fans of the franchise should have a pretty good time, and the newcomers who come with them shouldn’t be lost along the way.

“Insidious: The Last Key” is rated PG-13 for disturbing thematic content, violence and terror and brief strong language; running time: 103 minutes.