Pre-Production Unit- Developing a Storyline for Pre to Major Project

I have recently begun developing a storyline for myself and Charlie Ansell's short film. I wanted to create something that would allow us to tell a dramatic story, with a serious underlying message that would be able to be filmed and developed on a student budget, and I believe the story I have devised will allow us to do this.
Using the "Book Spine" rule that I found in "Pixar's 22 Rules of Story (That aren't really by Pixar)" I managed to create a storyline that I believe has the ability to be complex and dynamic enough to fit a the requirements for a short film, whilst still being interesting and compelling enough to keep an audience interested.

The story revolves around a couple that discovers that their child has become infected with a rare disease which causes the cells in the child's body to break down rapidly, which will ultimately lead to a very untimely death. There is no known cure, and as a result of the families desperation to save their child, they volunteer to take part in experimental clinical trials, with the hope that their child will somehow get better and be saved.
Miraculously the child eventually begins to recover and show an overall improvement in health. It seems that normality has returned until people, animals and plants living close to the child begin to fall ill and die. It is then revealed that the things that are deteriorating are losing their cells, and the child is somehow absorbing them to fix their own cells.
This angers the public and they then begin to subject the family to abuse, forming a hate campaign and eventually (when a massive amount of people have died) demanding that the child be killed. This causes the family to begin falling apart, disagreeing and questioning what is the right thing to do, with one eventually believing that the child should be killed so that everyone else may live, and the other not wanting to kill the child and instead working with the scientists forming the clinical trials to try and find a cure. This ultimately leads to a break up.
The film ends with the parent who originally didn't want to kill the child having a break-down and looming over the sleeping child with a pillow (presumably to smother the child) but cuts away to another scene before anything is done. The next scene shows the parent sat in silence in the park in silence, before dying- leaving the viewer to wonder whether or not the parent killed the child or not.

I specifically wanted to create an ending to this film which would be very ambiguous and allow the viewer to make their own mind up about how the film ended. I expect viewers of this film will be in one of two categories;

• Those who agree with killing the child in order to save everybody else in the world.
• Those who would not kill their child because they can't imagine taking their life.

I feel that the ending I have decided for this film will satisfy people with either one of these impressions and create a sense of gloom in both.