When making an adaptation, making changes to the source material does not have to be a cataclysmic affair. Take, for instance, Jurassic Park, a film that wildly veers away from the original novel in regards to tone, characters, and even major plot points, yet the film has ended up as more beloved than the book ever was. However, sometimes a singular change can completely destroy the intent of the original work, which not only can make the adaptation unfaithful, but also thematically muddled and thereby inferior. This is what seems to have happened in Z for Zachariah.
Though I have not read the novel of the same name, the parts of Z for Zachariah the film does a good job with are apparently those lifted straight from the page. Set in a post-apocalypse wherein seemingly nobody has survived (presumably after a nuclear war), Ann (Margot Robbie) is living alone on her family farm, trying to eke out a living by hunting local game and tilling her fields. While out hunting, she comes across a man, John (Chiwetel Ejiofor), bathing in a pool that she knows to be radioactive. She offers him shelter and nurses him back to health. Ann’s farm is seemingly protected from radiation due to a geographic anomaly, so she lets John stay and the two try to build a life together.
What’s remarkable about this scenario is that it plays out pretty much how one would think a scenario where two straight people of the opposite sex remain as the last living beings on Earth. They are ideologically opposed on a number of things: Ann is a religious and sentimental farm girl who only wants to remain comfortable with what she has, yet John is a scientist who wants to focus his efforts on rebuilding society, even given the meager resources at his disposal and what that might cost Ann. But the two are still drawn to each other in compulsively sexual ways, feeding into a biological need that is simultaneously romantic as it is creepy. It is an oddly compelling way to watch two people interact, particularly when one takes into consideration how vulnerable Ann is around John and how he could very easily exploit that, yet never crosses that tempting line.
But the film completely destroys that tension by adding a third character not found in the novel, Caleb (Chris Pine). Never mind the fact that Chris Pine is a poor excuse of an actor who is only remotely enjoyable when he’s imitating William Shatner, but this completely subverts the entire point of the story. Instead of exploring the ramifications of two strangers trying to build a life together, the film decides to contrive a love triangle that transforms its unique premise into a mundane soap opera. The character of Caleb is more ideologically similar to Ann, yet Ann sees more hope for her survival in John, and I was just waiting for one of them to turn out to be a werewolf or a vampire so that the Twilight parallels could be more blatant.
This film fails purely because of its wasted potential. It had a good thing going with its two-person cast, painting a dark and disturbing romance between uneasy strangers that works just fine as originally written. However, with the inclusion of an unnecessary third character whose actor couldn’t even bring anything to the role that the screenplay didn’t, the tension quickly unravels and the entire film’s thesis becomes buried in trite romantic clichés. Now if you’ll excuse me, I have what I’ve heard is a vastly superior novel to read.