The best advice to those who choose to spend 97 minutes of their lives on "Insidious: Chapter 3": Bring earplugs.

And maybe make better choices.

The "Insidious" franchise was already on fumes with "Chapter 2," and this prequel has nothing left but backfires to try to jolt viewers. Very, very loud backfires. It’s a physically painful experience, waiting for the sound mixer’s next assault. You know it’s coming, but it’s still a ball-peen hammer to the ears every time.

The first "Insidious," introducing us to a haunted family and psychic Elise and her ghostbuster friends, generated some mild creepiness before blowing it all in a third act that tried to explain everything. The second entry nose-dived into rehash. Why did they make a third? The second one’s reported budget was $5 million; it grossed about $162 million.

Credit where credit is due, the mysteriously well-reviewed "Insidious" and its first sequel play as an intended pair — "Chapter 2" sort of cleverly triggers traps laid in the original. But the prequel (written and directed by series co-creator and co-star Leigh Whannell, best known for his similar position in the "Saw" franchise) is such a shameless rolling of rubes desperate for a scare, the filmmakers don’t bother coming up with anything new.

The gag is thus: Teen and aspiring actress Quinn (Stefanie Scott) has been trying to contact her dead mother. As "Insidious" watchers know, that’s a no-no, and sure enough, something that is not Mom has gotten wind of her. Next up: the requisite long sequence of Dad (Dermot Mulroney) not believing her while Elise (Lin Shaye) decides to help.

"Chapter 3" is supposed to go further into "The Further," where mean ghosts await suckers with Ouija boards, but its deepest penetration is into touchy-feely land. In "Chapter 3," love is the answer. And darn it, belief in yourself. With precious little story to tell or scares to perpetrate, the film actually grabs for heartwarming in the end with sausage-like fingers. If that sounds ludicrous, it’s a major step up from Whannell’s "Saw" movies.

"Insidious: Chapter 3" is simply not scary. Not a bit, not a whit. Except that the audience will be terrified of the next stabbing of their eardrums, at generally predictable intervals. The most frightening thing about the third chapter is that it might be profitable enough to make a fourth.

Review by Michael Ordona, San Francisco Chronicle