Here is the basic idea for the movie i am trying to write, the story is fluid and can be changed.
NASA collect ice and rock specimens from another planet and then bring the samples back to earth. The planet samples returned to earth are stored in a laboratory for analysis by a team of scientists. A mosquito comes into the laboratory through an open window and then lands on the planet samples. The mosquito then flies out of the laboratory and bites a landscape gardener outside mowing the grass. The gardener bitten by the mosquito slowly changes metamorphic into an alien. The alien is shot dead, however, flies land on the dead alien and then the flies bite bystanders and this causes more people to change into aliens at a faster rate as the alien is evolving rapidly each generation. It is the end of the world and the only place to survive is inside a sealed biosphere that is a luxury living place oasis [The eden project]. Inside the biosphere the few scientist make a polymorphic bacteria to reverse the process and convert all alien life back to original earth life.
There is a lot more to the movie than just mentioned above.
How do I sell this?