Plot of Primal II

In the real world what would happen next is that the surviving girl would go to the authorities, they wouldn't believe her and send out a couple of officers to check it out.
When they don't return, they will start to suspect the girl and send a larger cohort to check it out. They will discover nothing untoward and the girl will be arrested for murder.
A sympathetic agent will believe her and somehow release her and they will both go back to try to discover what is happening.
They will uncover an ancient mystery and fight the bad thing.
The bad thing will adapt its' tactics and infect the girl in such a way that she is apparantly OK, but goes forth into the population to infect others.

I would like 25% of the takings please.

Thanks