The Line-Hall

Rachel lives with her mother on the Property.  Her mother works for Ms. Moore, a very stern, no-nonsense sort of women who raises orchids in her greenhouse.  They live in a futuristic time, the government has installed the Line-an uncrossable section of the National Border Defense system, an invisible barrier that encloses the entire country. The day the barrier was activated there were people caught on the other side. Ms. Moore's property it located right next to The Line and now someone is trying to make contact from the other side.  Who is it?  What do they want?