After a mysterious woman saves her daughter's life, a mother must do something unthinkable to repay the stranger.
TL:DR Rattlesnake is a perfect example of an entertaining premise, let down by poor execution.
I decided to put the tl:dr above for the sake of saving people from having to waste their time reading through the whole review to understand my thoughts on it, as this is how I felt about the film. There was so little satisfaction to be had at the conclusion of the film's runtime that it felt like I had just wasted my time watching it.
It is unfortunate because the premise is really intriguing. It follows along the lines of the overplayed myth revolving around making a deal with the devil at the crossroads. It is the questions that are raised by the requirements of the deal that could potentially hold the attention of the audience, along with the history of the location with this deal. Yet, none of this is thoroughly explored. The most interesting aspect of the entire film is drastically underutilised and leaves the audience with all questions unanswered.
Both directed and written by Zak Hilditch, one can't help but feel that Hilditch had a little too much pride in this story, and did not run the script through enough drafts as he could have. Our characters have very little in the way of character development, which is a huge wasted opportunity that spends near 60 minutes of an 85-minute film looking for the right person. Spending more time at the start of the film developing the relationship between the mother and daughter would help the audience care more about the fate of the characters, whilst reducing the amount of time spent aimlessly wandering around.
There is a poorly executed "ticking timer" element to the story. A deadline is set, but there is little in our main protagonist's behaviour to really give the impression of any tension, suspense, or pressure. There are frequent times when the deadline is reiterated, but what isn't focused on, is how much closer we are to that deadline. A deadline means nothing if you aren't following the progress of time towards it.
Our main protagonist, Katrina (portrayed by Carmen Ejogo) does do a good job with the script she is given and does try to play up the reluctance in what she needs to do. But without a solid connection to any of the characters, there is little to maintain the attention of the audience. The direction and cinematography are both adequate, however, the script was so skeletal that nothing is exciting.
Without the development of the protagonists, or exploration of the lore and history of the location, there is no emotional connection to the events in the film. It creates a film where nothing of note happens for 99% of the film, and is so poorly paced, that--even with a short 85-minute runtime--you will find yourself checking the clock to see how much longer the film has until it is over.
Rattlesnake is a wasted opportunity that I would recommend you avoid at all costs.