What is the time, place, conflict, and genre of Messenger by Lois Lowry?

Messenger is the third in a trilogy
of fantasy novels beginning with The Giver. Since it is fantasy,
there is no specific time or place in which the story occurs. The future (from the first
novel's setting) is the time in which the action occurs. The book refers to Village as
the place where inhabitants who were ill, crippled, or in some way deficient came to
live after being cast out of their previous towns. The problem in the story is that some
outside influence seems to be changing the villagers from their usual kindly selves into
quarrelsome, greedy individuals. In turn, Forest, an area that separates other towns
from Village, becomes an evil, twisted place that seeks to ensnare people as they
travel. This occurs after the inhabitants visit something called Trade Mart and barter
something unknown but personal for an objective they desire. The problem is solved, but
at great cost, by the main character Matty, who uses his unique healing abilities to
cure the ills of that fantasy world.