Whatever you do, don’t answer that shadow of a doubt whispering in your ear that maybe, just maybe, an unnecessary, unanticipated remake of a 1970s babysitter horror flick could be good. If you do, you may find yourself at the mercy of a frightening amount of boredom.

“When a Stranger Calls” is the latest cinematic regurgitation of an urban legend about the proverbial babysitter who receives threatening phone calls only to discover that they are coming from inside the house. The level of suspense resides somewhere between “Scream” and “Goosebumps,” but the level of imagination is more on par with a defensive driving video. The events of the story go beyond predictable. They have been all but embedded into the consciousness of contemporary viewers, so that watching the film is like a lengthy B-movie review session.

The film opens with an unobserved murder in Burford, Colorado, then jumps 125 miles to Fernhill, where teenager Jill Johnson has just learned that her father has disconnected her cell phone because “she went over her minutes.” Forbidden to attend a bonfire that draws all her friends away, she is stuck babysitting for the night at the home of the Mandrakis family.

The wealthy Mandrakises live in a spooky, secluded mountain pad filled with Expressionist art and plenty of dark corners. Their house is of pretentious architectural design — glass walls, an indoor garden and an alarm system to keep everyone safe. When Jill arrives, she is confronted with hurried, suspicious instructions and a list of phone numbers. The children, she is told, are upstairs sleeping and are not to be disturbed.

Jill is played by Camilla Belle, who landed the role presumably because she is a brunette B-cup who looks both young and mature enough to be believable as a babysitter. (By the way, Camilla, Brooke Shields wants her eyebrows back.) Camilla is as good an actress as Jill is a babysitter. Her character allows the garage door to remain open, plays dress up with Mrs. Mandkrakis’s jewelry and never checks on the children until the conventionally creepy voice on the phone reminds her to. Nevertheless, the film relies heavily on Belle’s adolescent screen presence; the rest of the actors could have (and in some cases, have) phoned in their performances.

Not long after Jill has settled in, the telephone starts ringing. Sometimes the caller is the slutty girlfriend, or the cheating boyfriend, but every now and then it is someone who neither speaks nor masks their loud breathing. Jill freaks and begins calling around, trying to figure out what she should do. Meanwhile, the music gets spookier and the housekeeper (a grossly stereotypical turn by Rosa Ramirez) suddenly disappears. Continuity also seems to dissolve — daylight fades and resurfaces according to whim, while the phone’s caller ID (a modern convenience tantamount to the story’s logic) is sometimes checked, sometimes not.

After latching onto the idea that she is being watched, Jill finally calls the police, who, after much ado about phone tracing, inform her that the caller resides somewhere in the house. In other words, Jill is as good as dead — unless, of course, she can avoid slaughter long enough for the police to arrive and save her.

The final cat-and-mouse game between stranger and babysitter consists of ample tricks that would bore an imaginative nine-year-old. Cheap, anticipated scare tactics (loud, sudden sound effects) and shadowy prop placement are responsible for most of the fright. Rated PG-13, “Stranger” also displays a dissatisfying level of violence. Not only is the body count too scanty by the end, the actual murders are unfortunately never witnessed by the audience.

It is not out of the realm of possibility that some viewers may find “Stranger” scary, in spite of its predictable plot and unoriginal composition. And while an element of surprise is systematically lacking, the movie still manufactures some thrills and chills.

But with a story that could never be much more than a practical joke, much less a truly terrifying experience, “When a Stranger Calls” belongs in the realm of forgettable fluff, right alongside most of the Sylvester Stallone canon and Jennifer Lopez’s resume.

Don’t answer. If you do, you’re bound to regret it.