At the beginning of “Maggie,” we’re told that life on earth has become bleak and without hope. The world as we know it has been plagued by a disease that turns humans into a flesh-eating zombies. This process, in which people undergo The Turn and lose all sense of who they were, has overcome much of humanity, though we’re never told how much of the world population is still normal. In a small farming town, a father named Wade is taking his daughter, Maggie, home from the hospital after she received a zombie bite. The news is bad: it’s only a matter of time before she becomes one of the undead, and the best remedy is to simply put her out of her misery. The daughter is played by Abigail Breslin and her dad is portrayed by none other than Arnold Schwarzenegger.

“Maggie” is in no way an action movie, but casting the former (and current) Terminator in the lead role makes sense. Instead of aiding the movie as one of the biggest movie stars in the world, what Schwarzenegger brings to his role is his experience as a father. Never before has he seemed so natural, relaxed and present in front of the camera. His chemistry with Breslin is also genuine and much of the film is made up of scenes between the two of them. While this is a horror movie, and there are some gruesome moments, it plays more like Cormac McCarthy’s “The Road” or the father/daughter scenes from “Interstellar.”

The real horror on display is the inability to stop the approach of death and of the body changing into something truly unnatural. Some of this reminded me of David Cronenberg as much as George A. Romero, as a gripping family drama unfolds in how the father cannot, will not, give up on his little girl. The story informs us of state mandated quarantine, as well as an “antidote”, both of which sound like inhumane death sentences. Schwarzenegger plays Wade as a quietly stubborn, unfailingly warm father who forces himself and those around him to just let whatever happens with Maggie to happen.

If there’s a subtext here to dissect, all one needs to do is simply remove the zombie angle: this is the story of a father who wants his daughter, who is overcome by a fatal disease, to die on her own terms and to be treated with humanity. If that sounds like a grueling movie, you’re right. “Maggie” is grim and slow, though its emphasis on character, and the way people cling to memory and feeling when they know they’re about to die, makes it a surprisingly humane, even existentialist take on the zombie genre.

There’s no need pointing out that Schwarzenegger can act. His work for Ivan Reitman and Paul Verhoeven proved that, as did “Sabotage” last year. Here, he not only engages with the role but gives himself fully to the tone of the film and his character. I knew his quiet, endearing performance worked when I often forgot about the actor and found myself worrying about Wade. Joely Richardson has some affecting scenes but the film belongs to Breslin and Schwarzenegger, whose last scene together put a lump in my throat.

“Maggie” is such a surprising film, not only in its casting but in its approach to the horror genre, it’s hard to say who the film is for. I fear a too tame for theĀ  horror crowd/too grisly for mainstream knee-jerk response could occur, which would be a shame. For all the talk and glimpses on screen of zombies, the story made me think of the brave, tender manner in which parents I’ve known with kids dying of cancer conducted themselves. I’m sure the similarity is intentional. There is beauty and compassion in “Maggie” that makes it a welcome standout.