I won't spend much time analyzing the plot, because it is simple. A bunch of guys, early-mid thirties, are up in a hunting camp. These guys were childhood friends that against all odds, including widely disparate abilities and avocations, remained friends. They shared a common experience in boyhood saving a boy with Down's syndrome from bullies. While they are up in the woods wondering around with rifles looking for Bambi to shoot, an alien spacecraft lands, and the aliens disembark.
Weird things begin to happen.
The military moves in. The alien moves out and takes interesting forms. The byrus invades one of the four friends, taking over his body and pushes the character to a corner of his own mind. Two of the four friends die early. I will have the good grace not to give you the entire ending, although there are few surprises .