Separation comes very close to being a great movie but never entirely finds its way there. It has real promise -- imagine Kramer vs Kramer as a horror story – along with sleek visuals and cool creatures. What it lacks is a willingness to go full-throttle in exploiting the potential of its central concept. There's much about the film that I enjoyed, even as I kept wishing it was just a little bit better than it ultimately is.

Jeff (Rupert Friend) is a washed-up comic book writer who briefly struck it big with a horror book he co-wrote with his wife Maggie (Mamie Gummer). Those glory days are gone now, and she's had to return to a regular job while he flails about professionally, trying to jump-start a career that is clearly dead. This creates friction within the marriage, leading Maggie to end it and take their daughter Jenny (Violet McGraw) with her. At the guidance of her father Rivers (Brian Cox), she files to get complete custody of the little girl and plans to move across the country so Jeff can never see her again. In fact, she is hell-bent on punishing him for everything he's ever done wrong.

The horror starts when Maggie is killed by a hit-and-run driver. Not long after, Jeff starts seeing his comic book creatures come to disturbing life in his dreams. Jenny, meanwhile, is unfazed. She begins playing with dolls inspired by those characters, whom she believes are her friends. These dual events begin to drive a wedge between father and daughter, as does the increased presence of babysitter Samantha (Madeline Brewer), who appears to have eyes for Jeff. To say any more would probably be a spoiler although I think you can guess from this description what the story's hook is.

Separation uses horror as a means of addressing divorce -- the petty games estranged couples play with each other, the psychological impact on children, the desire to "keep score" and assign blame, etc. All of those ideas are put into the context of the ghostly occurrences that transpire following Maggie's death. Times are especially difficult for Jenny, who now has to re-define her relationship with Jeff. The apparition she connects strongly with is the one he fears the most -- a black-cloaked figure that lurks around. The screenplay by Nick Amadeus and Josh Braun sets up several intriguing scenarios along those lines.

Similarly, director William Brent Bell (The Boy) nicely stages the creature scenes. Particularly effective is one in which a contortionist mime-like being stalks Jeff through the hallway, turning himself upside-down and in and out. Sure, this bit has been done in other movies, but the sinister way it's staged here makes it feel fresh. Later in the picture, Bell uses the color red to suggest the intersection of our world with the paranormal realm. His visualization of that is darkly elegant.

For all those good qualities, though, Separation isn't very scary. An excess of talky scenes causes the horror sequences to be too spaced apart. When they do arrive, none of them fully capitalize on the core premise (the one I'm being coy about). We should feel that Jeff is in grave danger from his own creations – that they fully intend to do him harm. The movie fails to establish that as strongly as it needs to. An obvious third-act revelation, meant to be a surprise, doesn't help matters any.

In the end, Separation deserves an A for ambition, but only a C+ for execution.

out of four

Separation is rated R for language, some violence and brief drug use. The running time is 1 hour and 47 minutes.