“Cobweb” is a horror genre piece as simple and to the point as its title.

A child hears noises in the walls of the old house where he lives, and in trying to raise the alarm with his parents, comes to wonder what their true nature is and just what they’re capable of.

First-time feature director Samuel Bodin proves sure-handed in dealing with the basics and produces a few truly hair-raising joles from Chris Thomas Devlin’s script.

But the odd dissonant note in a performance and stumbles in the plotting and especially the finale point to failures in execution and, when the chips are down, a loss of nerve.

Woody Norman, another moppet with the “child actor hair cut” (long, unruly) plays Peter, a lad bullied in elementary school and rattled by noises in the walls of his room at night.

His mother (Lizzy Caplan) teases his “over-active imagination,” and while his Dad (Anthony Starr) might give credence to the racket, he’s passing it off as “rats.”

But “rats” don’t whisper in a girl’s voice. Rat’s don’t pass on warnings about his parents, who won’t even let Peter go trick-or-treating, and aren’t shy about telling him of a girl down the street who disappeared on Halloween a few year’s back. Rats don’t coach Peter how to deal with the bullies at school.

With the bruises piling up at school and Peter doing chilling drawings in class in which he pleads “Help Me,” it’s no wonder his new teacher (Cleopatra Coleman) takes it on herself to check out his living situation and worry about his safety.

Virtually everything that happens in the third act summons up dusty, cobwebbed memories of the movies this one borrows from — a skittering, hairy monster of “The Ring,” masked intruders, a bloody showdown.

Caplan is the stand-out in the cast, hitting just the right shrill notes of the “a little…off” variety. But the kid’s not bad, Coleman’s properly plucky and Starr has his moments.

For a modestly-ambitious genre pic, “Cobweb’s” not all that original. But not that bad, either.

Rating: R, for horror violence and profanity

Cast: Lizzy Caplan, Anthony Starr, Cleopatra Coleman and Woody Norman

Credits: Directed by Samuel Bodin, scripted by Chris Thomas Devlin. A Lionsgate release.

Running time: 1:29