“Joshua” is the offspring of “The Omen,” “The Bad Seed,” “The Good Son,” and all the other goosebumpy thrillers about evil children, and like those movies, it’s at least as ludicrous as it is scary. It’s the carnival-fun-house kind of entertainment: genuinely creepy in some places, giggly in other places, and sometimes both at the same time.

Joshua (Jacob Kogan) is a precocious 9-year-old with a budding talent for the piano and a couple of wealthy Manhattanite parents, Abby (Vera Farmgia) and Brad (Sam Rockwell). Mom just had a new baby, and Joshua, a quiet, gentle soul, is experiencing some of the normal jealousy. He seems forlorn, too, more so after he learns that when he was born, Mom had some serious post-partum depression. When the new baby won’t stop crying, Abby starts to lose it all over again. She and Brad both wonder if the cycle is repeating itself.

Abby has a brother, Ned (Dallas Roberts), who’s a gay songwriter and pianist and Joshua’s major cheerleader when it comes to the arts. On the other side, Dad has a mother, Hazel (Celia Weston), who’s a fundamentalist Christian. She’s come to help out with the baby, which is bound to go well, what with the gay uncle in the family.

Then things begin to happen. Nothing supernatural — it’s not that kind of movie — but strange things nonetheless. The family dog is a target. A stuffed animal meets its end. Some of the auxiliary humans don’t fare well. And the title notwithstanding, part of the film’s suspense comes from not knowing for sure who the source of the strangeness is. Joshua’s behavior is odd but not creepy; certainly his mother, father, and the new baby are all possible factors, too. There’s a strong sense that something is wrong in this house — it’s the what, the why, and the who that are in question.

What eventually comes to light is a mouthwateringly twisted scheme, and there are two possible responses to it: You either get the chills, or you laugh. Or, I suppose, you could laugh as a means of shaking off the chills. Either way, director George Ratliff wants you to have fun with his gothic creation (co-written with David Gilbert), and he does solid work at keeping the movie tense and interesting even through some if its less plausible plot points. He was lucky to cast so many good, consistent actors in the leading roles, too, and they play everything with straight faces, believable to the end. Being a member of the comfortable upper class never looked so frightening!

B (1 hr., 45 min.; R, a handful of F-bombs, a little violence, general suspense.)