The purpose of trailers, those previews-of-coming-attractions that precede the feature at your lo cal multiplex, is to build anticipation for a new movie. But the trailers for "The Bodyguard" made it look just so-so, despite the presence of Kevin Costner and Whitney Houston.

However, I was completely unprepared for just how bad "The Bodyguard" is. With a screenplay by Lawrence Kasdan ("The Big Chill," "Grand Canyon," "Raiders of the Lost Ark," "The Empire Strikes Back") and direction by Mick Jackson ("L.A. Story"), as well as the presence of the aforementioned stars, the audience has a right to expect something more.

The story has a former Secret Service agent (Costner) free-lancing as bodyguard to high-profile (read "rich") clients, with one exception — he doesn't do show-biz types.

But after some coaxing, he decides to make an exception for an actress-singer (Houston, in her film debut) who is being taunted by an apparent crazed fan.

Naturally, Costner and Houston don't see eye to eye on his duties. He tightens security at her mansion, insists she not go out in public alone and generally tags along whenever she wants to do something he considers a breach of security — such as continuing her concert tour, attending the Academy Awards (she's nominated as best actress) or shopping.

There are sinister doings afoot, of course, and there may be someone inside Houston's camp who is harassing her instead of (or maybe in addition to) the crazed fan.

It would be easy here to reveal all kinds of "surprise" plot points here for the sake of making fun of the ridiculous storyline — which just gets sillier as it goes along. But I will restrain myself.

Suffice it to say that from Costner's bad haircut to Houston's negligible acting ability, from the never-ending closeups to the MTV-style editing, the people responsible for this picture just made one bad choice after another.

My two favorite scenes:

— A strange rendezvous at a snowbound mountain cabin, owned by Costner's father (played by Ralph Waite, the patriarch of "The Waltons" TV series). When they greet each other, it looks for all the world like an adult John-Boy coming home.

— The Academy Awards, a climactic thriller moment where Costner must figure out the mystery and save Houston's life — live on national TV, of course.

Suspending disbelief for this picture is a real chore. It might help if audience members can check their brains at the door.

On second thought, maybe it won't help at all.

"The Bodyguard" is rated R for language. There is also violence and a bedroom scene, but no graphic sex.