Horror is always a fun genre for storytelling, because it’s very freeing – especially when dealing with the supernatural. The kinds of attributes that filmmakers can attach to otherworldly antagonists are virtually limitless. Once those details have been established, however, it’s important that the film stick with the rules that it created for its universe. Case 39 features evil supernatural forces, but keeps adjusting the limits of the antagonist throughout the film, which prevents the movie from reaching its potential for something truly horrific.

Emily Jenkins (Renée Zellweger) is a social worker who takes pride in keeping children safe and giving them nurturing environments. Even though she’s overloaded with 38 cases, she still gives her new 39th case the same attention she would to any other. When she visits the family of Case 39, she meets the quiet and fragile Lilith (Jodelle Ferland) and her weird, shut-in parents. While Emily can’t see any signs of physical abuse, she senses danger surrounding Lilith and urges the little girl to call her if she’s in trouble. Lilith does just that and Emily rushes to her home just in time to stop Lilith’s parents from murdering her. Out of pity, Emily becomes Lilith’s temporary guardian, but as strange events and deaths begin popping up in Emily’s life, she quickly discovers that there are evil forces at work in Lilith’s life.

The overall mood created by Case 39 is excellently eerie. Lilith’s parents are creepy and backwards and are just odd enough to be unsettling. Lilith is also scary in the way that all children can be scary: they’re desires are extreme and it’s hard to know what they’re thinking. Jodelle Ferland seems to be made to play disturbing kids and has finely honed her deadpan expression and wide-eyed stares to accentuate her clear blue eyes and betray nothing about what’s going on inside her head. Everything about Lilith’s home life is hair-raising, especially the parents’ bedroom with the huge deadbolts on the door and deep scratches in the wood floor where heavy furniture is moved night after night as a makeshift barricade.

The rest of the film doesn’t quite fully capitalize on this excellent foundation. The supernatural forces in the film don’t operate with any discernible rhyme or reason, thus making it difficult to know how Emily is supposed to combat it. Sometimes the monster has trouble getting through a barricaded door. Other times it can just magically appear inside a locked vehicle. Other times a barricaded door is easy for the monster to break through, yet later in the film Emily thinks that tying a door shut with rope is enough. Also, what is the point of the barricades when Emily and the parents have to interact with Lilith during other hours throughout the day, leaving them vulnerable?

The scares in the film are mostly the cheap, but fun kind. Characters will be distracted, looking intently at one thing and then they’ll turn around and suddenly there’s someone there! But it’s just a friendly policeman. Oh, but what’s that?! It’s just a barking dog on the other side of the window. Each time something suddenly enters the frame the audience is assaulted by a loud sound – known as stingers – that will definitely get viewers jumping. It would have been nice, however, if more of the scares weren’t so innocuous and originated from the monster. There also isn’t much gore, which will please some moviegoers while leaving others wanting.

Renée Zellweger does a good job as Emily and she transmits her plight well as it degrades from bliss to frustration to fear and finally to surrender. Unfortunately, the script doesn’t do much to develop her character beyond a woman caught in an extraordinary situation. Audiences don’t really get to see her change from a woman who loves children to someone who would do the unthinkable. Nevertheless, Zellweger doesn’t disappoint.

Regarding the writing, the story misses some opportunities to develop Lilith and extend the theme beyond woman versus creature. Is Lilith evil incarnate or is there still a 10-year-old girl in there who’s trying to be normal, but deals with the struggles of growing up with her powers because she can? Also, there are a few religious references throughout and layman even describes the monster as a demon, but Case 39 stops short of making this a God verses the Devil situation, which would have raised the stakes nicely.

Case 39 is pretty straightforward as far as horror movies go. It will have viewers jumping, recoiling and closing their eyes, but it doesn’t quite get under the skin as deep as it should. Stricter adherence to its own rules and a focus more on Emily’s story and transformation would have gone a long way. Overall, however, Case 39 still delivers the thrills and scares that will satisfy most horror fans.